Introduction

The field of family therapy increasingly requires flexible, accessible therapeutic approaches that can meet the needs of families navigating complex problems, such as trauma-related distress (Papero, 2017). Families affected by trauma often face relational disruptions, elevated stress, and practical barriers that may limit their capacity to engage in traditional multi-session models of care (Hoyt et al., 2021; Kiser et al., 2010). Brief, responsive interventions that can accommodate these constraints while remaining aligned with trauma-informed and systemic principles are therefore essential for effective family-based work. Developing consensus-informed guidance on how Single Session Thinking (SST) may be safely and appropriately applied with trauma-affected families represents an important step toward meeting this need. This study reports findings from a modified Delphi inquiry examining the use of SST in family therapy with trauma-affected families.

Family and Systemic Perspectives on Trauma and Recovery

Trauma reflects a rupture or loss of connection to oneself, family, and world following exposure to events that exceed a human’s capacity to cope and make sense of the experience (Levine & Frederick, 1997). The spectrum of traumatising events spans singular exposure to a traumatic event (e.g., serious accident, isolated threat to safety, exposure to community violence) through to prolonged, relationally based, ‘complex’ trauma (e.g., violence or abuse within relationships of dependence). For some, exposure can lead to a trauma- and stressor-related disorder, the most prevalent of which is posttraumatic stress disorder (American Psychiatric Association, 2013). Beyond a diagnostic lens, the impacts of trauma are pervasive and systemic, affecting thought, capacity for self-efficacy and self-leadership, and importantly, trust in others (van der Kolk, 2014).

Although treatment for the effects of trauma have historically focused on the individual (Cusack et al., 2016; Jericho et al., 2022; Lewis et al., 2020; Roberts et al., 2019; Watts et al., 2013), trauma experiences always contain an interpersonal and systemic component in origin and/or in impact (Figley & Figley, 2009; Grove, 2021; López-Zerón & Blow, 2017; Papero, 2017). Irrespective of whether trauma begins as a relational event, or sits within or beyond the family context, trauma of any kind can have wide ranging impacts on the relational health of individuals and their important social and familial networks (Grove, 2021). Family therapy may improve outcomes for individuals or families affected by trauma through several interconnected mechanisms (Grove, 2021). The practitioner’s systems lens can promote effective patterns of responsiveness within the family, enhancing capacity to mobilise internal resources and create a more supportive relational environment for those experiencing trauma-related difficulties. In turn, greater responsiveness, support and understanding within family systems can reduce individual and system stress (Papero, 2017). By supporting the development of more adaptive relational and emotional responses to family challenges, family therapy may reduce the risk of ongoing or future vulnerability within the family unit, contributing to long-term systemic resilience (Grove, 2021; Papero, 2017). Thus, the growing recognition of trauma’s systemic effects, together with evidence for the central role of relationships in recovery (Brewin et al., 2000; Prati & Pietrantoni, 2010), underscores the need for evidence-based contextual and relational approaches to trauma. Such approaches should ideally integrate the experiences of all family members, foster reconnection, and strengthen family networks.

The State of Evidence in Family-Inclusive Trauma Recovery

The merit of trauma-informed approaches to mental health care is well established (Butler et al., 2011; Clark, 2014); however, the application of trauma-informed principles to family therapy, and the progression of evidence for trauma-informed family therapy, remains scant. Early work was theoretical in nature, converging on the call for family-inclusive treatment and healing approaches to trauma that aimed to repair family-related challenges linked to problematic individual and family-level functioning (Champine et al., 2018; Collins et al., 2011; Coulter, 2013; Diamond et al., 2016; Figley & Figley, 2009; Kerig & Alexander, 2012; López-Zerón & Blow, 2017). Several non-randomised feasibility or effectiveness studies have also been conducted evaluating manualised, trauma-informed interventions for families, with demonstrated reductions in child and parent symptoms of emotional distress, behavioural problems, PTSD (Kiser et al., 2010, 2015; Papero, 2017) and overall improvements in caregiver, child, couple and/or family wellbeing (Collins et al., 2015; Goff et al., 2020; MacIntosh, 2024). Further, meta-analysis of four randomised controlled trials evaluating couple and family therapies for posttraumatic stress disorder have similarly supported a reduction in trauma symptoms for the affected individual, however more evidence is needed to determine the impact of the interventions on relationship quality or mental health of family members (Suomi et al., 2019).

However, barriers to engagement in multi-session models of trauma care are high for individuals, and higher still for families (Hoyt et al., 2021). Meta-analytic evidence shows dropout rates for individuals who have started trauma treatment of between 25 and 75% (Benish et al., 2008; Imel et al., 2013; Olfson et al., 2009; Saxe et al., 2012), and just over half of families are likely to complete family-inclusive trauma interventions (Kiser et al., 2010). Treatment flexibility is thought to be crucial in preventing treatment dropout, with collaborative, empowering care requiring adaptable and client-responsive approaches (Benish et al., 2008; Grove, 2021). Evidence for family inclusion and the need for timely, flexible approaches to engagement in trauma care both suggest the potential suitability of single-session family approaches (Rycroft & Young, 2021; Young et al., 2012).

Possibilities for a Single Session Thinking Approach

Single-session thinking (SST), as it is applied to mental health settings, is a service delivery model based on three evidence-based principles: (a) irrespective of the nature, complexity or severity of the presenting problem, the most common number of service contacts by clients is one (followed by two, and so on); (b) any single session can yield meaningful benefit or change; and (c) it is not possible to predict who will attend beyond their first session (Schleider et al., 2025; Young, 2020). Single-session thinking is thus not a specific model of therapy, but rather a mindset held by both the therapist and the client/s that the first session may also be the only session and that many clients find one session sufficient (Cannistrà, 2022). While further sessions can be offered (and indeed, SST is just as relevant when applied to multi-session work compared to brief interventions), the underlying attitude of both therapist and client is to make the most of their present encounter, which is thought to allow for transparency and authenticity about the process of therapy and a greater co-design in the therapeutic agenda (Cameron, 2007; Elliott et al., 2020; Young, 2020). Advocates for SST describe the approach as an “accessible, timely, and responsive service which invites clients to have a voice in what they most need, and when” (Rycroft & Young, 2021).

Rycroft and Young (2021) developed an SST session map which has been used as a tool for teaching SST to practitioners, providing a guide for its application as a service delivery model while allowing flexibility for practitioners to integrate their preferred theoretical approach and therapeutic style. The session map emphasises client engagement, collaborative goal-setting, and reflective closure, progressing through six key stages: establishing context and priorities; maintaining focus through check-ins; exploring past solutions and client strengths; allowing reflective pauses; and concluding with therapist reflections, client feedback, and closure. Each stage includes guiding questions designed to promote transparency, alignment with client needs, and shared decision making, fostering an interactive and responsive therapeutic dialogue while reinforcing client agency (Rycroft & Young, 2021).

As the field has expanded, single-session approaches have been increasingly applied across diverse service settings, presenting problems and subpopulations (Schleider & Beidas, 2022; Schleider & Weisz, 2017). A growing body of evidence supports its effectiveness in family therapy, demonstrating improvements in problem resolution, client confidence and overall satisfaction (Batrouney, 2019; Hartley et al., 2023; John Westwater et al., 2020; O’Neill, 2017; Perdomo, 2017). For example, a recent pilot study of a walk-in family therapy clinic, grounded in single-session principles, included families facing a range of challenges, with approximately one third of the families seeking support after a family member had experienced a traumatic event. The pilot study found that six-weeks after attending, 88% of all families felt confident in knowing what to do next, and 69% of families reported that the session had helped resolve the issue they initially presented with (Hartley et al., 2023). The findings from Hartley et al. (2023) align with published case studies further indicating the effectiveness of single-session approaches for trauma-affected families (Batrouney, 2019; Perdomo, 2017).

Although initial findings suggest potential benefits, there remains a lack of replicated evidence examining single-session approaches specifically designed to address trauma-related symptoms in either individual or family contexts (Schleider et al., 2025). One possible reason for this gap is the longstanding caution surrounding brief trauma interventions, largely stemming from adverse outcomes associated with Critical Incident Stress Debriefing (CISD; (Stileman & Jones, 2023). Unlike more contemporary single-session approaches, CISD involves encouraging individuals to revisit traumatic events soon after they occur and typically fail to address cumulative stressors – a practice misaligned with current evidence-based, trauma-informed and systemic care. In contrast, brief interventions such as written exposure therapy (while not formally aligned with SST), have shown comparable effectiveness to lengthier treatments for posttraumatic stress disorder (Held et al., 2019; Sloan et al., 2022). Additionally, single-session, solution-focused interventions have been adapted for use with trauma-affected populations in resource-limited humanitarian settings (Paul & Ommeren, 2013). Given this context, developing empirically grounded approaches to guide the use of SST for trauma-affected families represents a critical direction for future research.

Study Aims

As a next step, we sought to better understand the benefits and possible constraints of SST for trauma-affected families. Because SST functions as a service-delivery orientation that can be applied across therapeutic models, the study did not evaluate SST within the context of any particular family therapy model. Instead, a modified Delphi method (Keeney et al., 2011) was used to: (1) explore expert perspectives on the suitability of SST for family therapy with trauma-affected families, and (2) examine areas of consensus to inform guidelines for applying SST in this context, including adaptations to the SST session map (Rycroft & Young, 2021) for use with trauma-affected families.

Methods

Study Design, Sampling Strategy and Setting

To develop guidelines for applying SST to family therapy with trauma-affected families (Aim 1), this study utilised a modified Delphi approach. The Delphi methodology is a structured and iterative approach to soliciting expert opinions and reaching consensus on complex topics. It is often used in areas where there is uncertainty or disagreement among experts, such as identifying best practices in a particular field (Keeney et al., 2011), making it a suitable approach to address the aims and objectives of this proposed study. Using the Delphi method, data was collected using a series of questionnaires administered to a group of experts to identify areas of consensus and disagreement regarding the suitability and application of SST to family therapy with trauma-affected families. In this study, one round of interviews and two Delphi questionnaire rounds were completed because of the exploratory nature of the study, and to mitigate panellist dropout caused by fatigue. Qualitative descriptive analysis of an open-ended question regarding the adaptation of the SST map for trauma-affected families was used to address Aim 2.

The selection of expert participants is a critical component of the Delphi method, as the quality of outcomes relies heavily on the participants’ depth of knowledge and expertise (Fish & Busby, 1996). Therefore, this study employed purposive sampling to recruit an expert panel of family therapists with substantial experience of working with families affected by trauma and the application of SST. This ensured that the panel consisted of individuals with the specialised knowledge required to contribute meaningfully to the Delphi process. Potential panel members were identified based on their qualifications, years of experience, and familiarity with SST. Inclusion criteria required participants to have: (a) an advanced degree in family therapy (Graduate Certificate or Master of Family Therapy); (b) formal training in SST and practical experience in its application; and (c) clinical experience and theoretical knowledge of family therapy with trauma-affected families. This targeted selection process maximised the likelihood of obtaining insightful, practice-informed perspectives relevant to the study’s objectives. The Bouverie Centre, established in 1956, is a research centre and a state government funded clinical service located in an urban suburb of Brunswick, Melbourne (Australia). Family therapy sessions can be offered via telehealth, supporting accessibility for families located regionally or rurally. Expertise of the Centre includes family-inclusive practices to mental health care, SST clinical approach and evidence, and relationally oriented trauma work (Booth et al., 2024; Clancy et al., 2020; Elliott et al., 2020; Hameed et al., 2023; Hartley et al., 2023; Kestly et al., 2024; Krella et al., 2025; McIntosh et al., 2021; McLean et al., 2021; O’Hanlon & Rottem, 2021). The initial SST family therapy session at the Centre is delivered in a 90-minute format, with any subsequent sessions conducted in the standard 50–60-minute timeframe. The clinical service is provided at no-cost to families, and is therefore able to support families from a diverse range of socioeconomic and cultural backgroundsin which a member experiences a serious mental illness, substance use issue, or significant trauma, including single-event trauma (e.g., car accidents, physical assault, natural disasters), sexual trauma, traumatic loss, complex trauma, and their intersection. Given this expertise, the Bouverie Centre provided an ideal setting for recruiting family therapists onto the study’s participant panel.

Ethics Approval

This study was approved by the La Trobe University Human Research Ethics Committee (HREC: 24425). Participants were provided with a written information statement detailing the study purpose, procedures, risks, confidentiality, and voluntary nature of participation. Written informed consent was obtained prior to participation. Consent included agreement to participate in multiple Delphi rounds and for de-identified data to be used in publications.

Participants

Of the 25 expert panel members invited to participate, 16 agreed to participate, and completed the first round. Eleven completed the entire study, resulting in an overall response rate of 69%. Non-participation or incomplete participation was primarily due to non-response to follow-up invitations related to competing personal and professional commitments, including staff leave. As shown in Table 1, the panel was predominantly female (81.3%) and over the age of 46 (90.8%). All panel members were either current or former family therapists at the Bouverie Centre, held a postgraduate qualification in family therapy, and more than half (62.5%) had over 20 years of clinical experience as family therapists. All panel members had extensive experience working with families affected by trauma across diverse settings, including community mental health services, specialised family violence and sexual assault services, forensic mental health, child and family therapy centres, and government-funded programs. Their expertise encompassed trauma across the lifespan, including childhood sexual abuse, family violence, complex developmental trauma, intergenerational trauma, and the impact of parental mental health and substance use. All panel members had completed training in SST, with half (50%) also having facilitated SST training for other allied health professionals (n = 8). Additionally, two-thirds (68.8%) of panel members reported applying SST in more than half of their work with trauma-affected families, highlighting the approach’s predominance in their practice.

Procedure

The Delphi study was conducted over three rounds: one generative pre-test round of four qualitative interviews with a subset of the expert panel, and two rounds of the Delphi Questionnaire.

Generative Pre-test Round

In the first phase of the Delphi study, individual interviews with four members of the expert panel were conducted with the aim of generating ideas and statements about the topic that could become items and domains for inclusion in the Delphi questionnaire. These four participants were purposefully selected based on their established expertise in trauma and their senior roles within the centre, ensuring that the initial item pool was informed by clinicians with substantial knowledge of both systemic trauma practice and SST. This approach is commonly used for creating Delphi questionnaires when the topic is relatively unexplored(Keeley et al., 2016).

The interviews were conducted by a student completing the research component of a Master of Clinical Psychology with the Centre, and was not known to the expert panel members. Interviews were completedvia videoconferencing and lasted approximately 45–60 min each. The interview guide consisted of eight open-ended questions designed to elicit insights about the role of SST in family therapy with trauma-affected families (see Supplementary Information); challenges and benefits of SST when working with trauma-affected families; key competencies, principles, and factors influencing the effective application of the SST framework with trauma-affected families. Interviews were audio-recorded and transcribed verbatim, before two members of the research team (ZC and NB) examined the transcripts.

Descriptive analysis was used to summarise and identify themes, issues or statements relevant to the suitability and applicability of an SST framework to trauma-related family presentations. These were then collated and synthesised into statements which were used to construct questionnaire items and domains for the Delphi questionnaire, with great care taken to retain the original meaning and wording of participant responses. Another member of the research team with experience in conducting Delphi studies (EW) then reviewed a draft of the questionnaire to remove redundant items and ensure clarity, comprehension and face validity before distribution to the full Delphi panel.

This process resulted in a Delphi questionnaire containing 51 statements across the following categories: structural features of the SST framework that facilitate family therapy with trauma-affected families (n = 11 statements); the role of the therapist when applying SST to family therapy with trauma-affected families (n = 23 statements); family and contextual factors relevant to SST with trauma-affected families (n = 11 statements); and, theory of change when using SST in family therapy with families affected by trauma (n = 6 statements).

Delphi Questionnaire Round 1

A link to the finalised online Delphi questionnaire was emailed to the expert panel. Panel members were asked to answer a set of demographic and qualifying questions (age, qualifications, years of experience, and experience applying the SST framework and experience working with families affected by trauma). Then, panel members rated the perceived importance of each of the 51 statements of the Delphi questionnaire using a 7-point Likert scale. For example, panel members were instructed to consider the statement “when working with families affected by trauma, it is important that the SST structure creates containment through clarity and transparency” and indicate its importance on a scale of 1 (not at all important) to 7 (essential). A final open-ended question was included which presented the panel with the Rycroft and Young (2021) SST session map and asked if they would adapt any aspect of the map when working with a family affected by trauma. Responses were subsequently analysed using qualitative descriptive analysis.

Responses were deidentified and analysed to determine those that had reached consensus. Noting Delphi consensus definitions vary by study context (Hsu & Sandford, 2007), we defined consensus as an interquartile range (IQR) less than or equal to 1, indicating a very high degree of consensus among the expert panel as to the importance of a particular statement. Additionally, statements were classified as essential if the median response rating was 7 and achieved consensus. Statements lacking consensus in Round 1 were redistributed to the expert panel in a second-round survey.

Delphi Questionnaire Round 2

A second online questionnaire was developed, containing 21 statements from the Round 1 Delphi questionnaire that had not reached consensus. Panel members who participated in Round 1 were emailed an invitation with a link to the Round 2 Delphi questionnaire and a personalised PDF “Participant Response Summary”. The Participant Response Summary included a table listing all statements that had not reached consensus (i.e., IQR > 1), along with that specific panel member’s previous response (rated from 1 to 7) and the mean and range of responses from all other panel members for each statement. Panel members were instructed to use the Participant Response Summary to review their prior rating of these statements considering the group’s feedback to consider re-rating each statement on the same 7-point Likert scale. Data collection for Round 2 remained open for four weeks, after which the responses were deidentified and re-analysed to determine any further statements that had reached consensus.

Finally, across a series of iterative workshops, three authors (ZC, NB, and EW) reviewed the 36 statements that had reached consensus and undertook a descriptive thematic analysis to reorganise them into conceptually coherent categories. The authors independently examined each statement, identified its primary focus (e.g., engagement processes, safety considerations, session structure, therapeutic posture), and generated preliminary thematic groupings. Through discussion, the authors compared interpretations, refined category boundaries, and consolidated overlapping or conceptually similar clusters. The final categorisation reflected areas of shared meaning across statements rather than the original domains used in the Delphi survey. This process resulted in a set of practice guidelines aligned with SST session goals, therapeutic posture, and techniques that support change and healing. To minimise the risk of researcher bias, a fourth team member (JM) independently reviewed the resulting guidelines for clarity, theoretical relevance, internal consistency, and redundancy, ensuring that each statement was distinct, meaningful, and aligned with the overarching principles of SST and family therapy practice.

Results

Out of 51 statements assessed in Round 1, 30 statements (59%) achieved consensus, while 21 statements (41%) were redistributed to the expert panel for further evaluation in Round 2. After completing both rounds of data collection, 36 statements (71%) reached consensus. Of those that reached consensus, all had a median of 5 or higher, and 67% of these were classified as “essential”, having achieved a median rating of 7. Of the remaining 15 statements that did not achieve consensus, all had a median of 5 or higher but with greater variance (IQR > 1). Table 2 displays an overview of the number of statements within each category of the Delphi questionnaire that achieved consensus and was considered essential.

As seen in Table 2, the highest proportion of statements that reached consensus related to the therapist’s role in applying SST, while the theory of change category had the highest proportion of statements deemed essential. In contrast, the lowest proportion of statements achieving consensus (indicating the highest level of disagreement) was found in the category addressing family/contextual factors that could impact the application of SST to trauma-affected families. This category also had the lowest proportion of statements considered essential. Figure 1 contains the list of 36 statements that reached consensus and were classified as essential in the format presented to the expert panel. Through discussion and workshopping between the research team, these essential statements were then re-categorised into a set of practice guidelines relating to the SST session goals, posture, and techniques that promote change and healing (Table 3).

Essential Statements Following Two-Rounds of Delphi Questionnaires

Finally, open-ended responses to the final survey question were analysed using descriptive qualitative analysis, systematically categorising expert feedback according to the existing SST map components. Patterns and common themes were identified, summarised, and integrated into a revised SST map tailored for application in family therapy with trauma-affected families (Fig. 2). Figure 2 retains the original clockwise sequencing of the SST session map (Rycroft & Young, 2021). Although the order may initially appear reversed, it follows the visual logic of the original model, which was designed to be read in a circular, clock-like progression. As illustrated in Fig. 2, the proposed adaptations to the SST session map highlights the aspects of SST that are amplified to enhance safety and responsiveness when working with trauma-affected families. For example, 54% of panel members recommended the addition of a new pre-session step to assess risk and determine the need for subsystem work to promote containment and safety. This included clarifying who would attend the session (e.g., whether it was appropriate for children or individuals who had used violence to be present) and considering the session format (e.g., in-person vs. telehealth; shared vs. separate screens).

The second phase of the map was revised to explicitly overt the importance of emotional and relational safety throughout the session. This involved collaboratively identifying emotion regulation strategies, discussing the impact of trauma on communication, and co-developing distress signals (e.g., verbal cues or gestures). Brief psychoeducation on nervous system responses was suggested to support self-awareness and normalisation of emotional activation. To ensure safety, the expert panel emphasised the importance of “talking about the talking” – guiding families to focus on the relational impacts of trauma rather than detailing traumatic events. Establishing a conversational frame rooted in curiosity, care, and containment was seen as critical for engagement.

Ongoing check-ins throughout the session were also strongly endorsed. Expert panel members highlighted the need to monitor each family member’s emotional state throughout the session, including the option to briefly pause or separate family members if needed. Some suggested integrating neurophysiological or polyvagal-informed check-ins to assess whether participants remained within their “window of tolerance”. These check-ins were seen as guiding whether to continue with systemic dialogue or shift to regulation-focused interactions.

Further, the original map’s pairing of “investigating attempted solutions” with “listening for client resources” was reconsidered. For trauma-affected families, the expert panel recommended shifting emphasis toward identifying resilience, resistance, and healing by asking relational and systemic questions that highlight individual and collective strengths, and to reflect these back to the family to reinforce agency and hope. Finally, the last step of the session map was expanded to include closing reflections on present-moment awareness and grounding. The expert panel suggested asking how family members were feeling “right now” and to guide them in identifying post-session self- and co-regulation strategies. This was intended to reinforce emotional self-awareness and promote wellbeing beyond the session.

Discussion

This study aimed to identify and analyse specialist practitioner recommendations on the suitability of SST as a service-delivery model for family therapy with trauma-affected families and to examine necessary adaptations to the existing SST session map (Rycroft & Young, 2021) to enable more targeted support for families presenting with trauma-related experiences. Overall, findings suggested: (a) preliminary, consensus-based evidence of SST as suitable for family therapy work with trauma-affected families, (b) suggestions of where existing SST methods should be amplified, and (c) additions to existing practice. Informed by current findings, the study offers new practice guidelines and an adapted session-map ready for further evaluation and implementation by diverse service providers working systemically with families affected by trauma in brief or single-session formats.

SST as a Suitable Approach for Trauma-Affected Families

Findings from the Delphi process offer preliminary evidence that SST is a suitable and adaptable service delivery model for family therapy in the context of trauma. Most statements within each category of the Delphi questionnaire achieved consensus among the expert panel, with a high proportion of statements across categories rated as essential to the application of SST to family therapy with trauma-affected families. Overall, the expert panel endorsed the value of SST’s clear structure, collaborative stance, and contained format as strengths when working with trauma-affected families. This reinforces previous research supporting SST’s flexibility and potential for therapeutic depth within a single encounter, even for complex family presentations such as trauma (Elliott et al., 2020; Young, 2020). Further, findings align with preliminary studies that have evaluated the effectiveness of single-session approaches among families whereby trauma-related presentations represented a significant proportion of their sample (Batrouney, 2019; Hartley et al., 2023; Perdomo, 2017).

An important finding of the Delphi study was that the category concerning contextual or family-related factors relevant to the use of SST with trauma-affected families received the lowest level of consensus among expert panel members, and produced the fewest statements deemed essential for inclusion in the final practice guidelines. One interpretation of this outcome is that it reflects the inherent variability among families who have experienced trauma. Unlike service-specific, therapist or theory-driven considerations, where consistent practices may be more readily generalised, family-level factors are highly context-dependent. Trauma does not affect all families in the same way, and as such, factors such as family structure, dynamics, communication patterns, cultural background, and readiness to engage in therapy can vary significantly (Grove, 2021). Thus, while expert agreement on family-centric elements was limited, this variability itself offers an important insight that aligns with trauma-informed care: SST with trauma-affected families must remain flexible and attuned to the constellation of needs, strengths, and vulnerabilities within each family system.

Refinements and Additions To Existing SST Practice with Trauma-Affected Families

The study identified key ways in which SST can be refined to better support families affected by trauma, particularly by enhancing emotional and relational safety. Experts emphasised the value of using the SST structure to create a clear, containing environment from the outset, through transparent framing of the session’s purpose and careful pacing to avoid re-traumatisation (especially in cases of intra-familial trauma). A trauma-informed therapist posture was seen as critical, marked by open communication, sensitivity to family expectations, and intentional trust-building within the time-limited format.

These priorities were further reflected in expert suggestions for adapting the SST session map. Recommendations included more robust preparation, such as pre-session assessments of risk and readiness, as well as more frequent, nuanced in-session check-ins. Panellists strongly endorsed ongoing monitoring of each family member’s emotional state, with some advocating for the addition of polyvagal- or neurophysiologically-informed practices to assess whether participants remained within their “window of tolerance”. Systemic application of polyvagal theory to families affected by trauma frames unhelpful relational behaviours (e.g., defensiveness or withdrawal) as adaptive responses to nervous system activation (Porges, 2011; Ryland et al., 2022). Within a single-session family therapy context, this understanding could help therapists quickly normalise trauma-related reactions, reduce blame across family members, and establish a sense of safety and co-regulation within the therapeutic encounter. While such strategies are well established in trauma-informed care (Porges, 2011), the present findings represent a promising line of future refinement for SST. Further empirical studies investigating mental health and relational outcomes for trauma-affected families following SST could continue this work, thus contributing to a growing body of work that bridges systemic, trauma-informed, and body-based approaches to single-session family therapy (Grove, 2021; Porges, 2011, 2022; Ryland et al., 2022).

Practice Implications

The clinical and practice implications of this study are noteworthy. The findings provide preliminary indications that an adapted SST approach may be useful for work with families affected by trauma. The practice guidelines developed through the Delphi process offer a provisional framework for therapists, outlining ways to create safety, recognise the body’s responses to trauma, and build trust and connection – all within a structured yet adaptable single-session format. These recommendations may be particularly relevant in high-demand service environments, including community mental health and child and family services, where brief interventions are often necessary and where a single encounter may serve as a critical point of therapeutic engagement. Implementing these adaptations will likely require thoughtful investment in workforce development. Practitioners working within an SST framework with trauma-affected families may benefit from targeted training and supervision related to the updated practice guidelines and SST session map, given the heightened complexity that can arise when trauma is present in the family system.

Finally, the study’s findings reinforce the potential of SST to support service equity by improving access to meaningful therapeutic support for families who might otherwise be excluded from more traditional, longer-term care due to socioeconomic, geographic, or service barriers. Together, findings contribute to the ongoing development of SST as a flexible, responsive, and inclusive model of care, with clear expert consensus that a well-structured single session can offer meaningful therapeutic impact, even in complex, trauma-affected family presentations.

Strengths, Limitations and Future Research Directions

Several strengths and limitations should be noted. A key strength of the study lies in its focus on a novel and underexplored area of applying SST to trauma-affected families and its engagement of a highly experienced and specialised expert panel. The outcomes of the Delphi process are practical and targeted, providing a clear foundation for future development and empirical testing. The study design utilised purposeful, criterion-based sampling to recruit experts from a single institution with a strong history of research, workforce uplift and clinical implementation of SST and family therapy with trauma-affected families. While purposeful sampling is appropriate for a Delphi design, sampling from a single institution limits the transferability of the findings to practitioners working in other organisational contexts. For example, because the expert panellists all work within a model that provides a 90-minute initial SST session, it is not clear whether some trauma-informed SST adaptations (e.g., the addition of an initial conversation specifically establishing emotional and relational safety) would need to be further adjusted when implemented in settings where the initial session is limited to the standard 50–60 min. To strengthen the transferability and validity of the proposed adaptations, future research should extend this work across diverse clinical contexts (including involvement from clinicians working within different session-length structures), while also actively involving trauma-affected families in the evaluation process using applicable, trauma-informed, outcome measures.

Conclusion

This study offers timely insights into the application of SST with trauma-affected families. It confirms the relevance and utility of SST in this context while identifying key areas for refinement and innovation. The resulting practice guidelines and revised session map represent an important step toward a more trauma-responsive, relationally attuned model of single-session family therapy. Future research and practice development can now build on this foundation to further integrate trauma-informed principles within brief, targeted, systemic and therapeutic frameworks such as SST.