A Constructivist Grounded Theory Study Protocol: What works for whom? Therapists and adolescents perspectives on indication criteria for schema therapy

Aim: Schema Therapy (ST) is an evidence-based treatment for complex mental health problems rooted in early Adverse Childhood Experiences (ACEs). Although both individual and group formats have shown effectiveness, little is known about which format works best for whom. This question is particularly relevant for adolescents given their unique developmental needs. Despite over a decade of clinical experience with ST in adolescents, current research offers limited guidance on how to tailor the format to individual needs - resulting in a persistent gap between research and practice. This study aims to develop practice-based indication criteria for individual versus group schema therapy by integrating therapists expertise with experiences from adolescents who underwent ST. Methods: This qualitative study employs a constructivist Grounded Theory approach. Data will be gathered through focus group discussions with schema therapists and individual interviews with adolescents. Therapists will be purposively selected based on experience with both therapy formats and with traumatized adolescents. Adolescents are eligible if they have experienced ACEs and have completed at least 20 sessions of ST. Results: The analysis will result in a theoretical model that integrates therapists clinical reasoning and adolescents preferences. Conclusions: This study integrates schema therapists expertise and adolescents lived experiences to develop actionable indication criteria for choosing between individual and group ST. By supporting informed clinical decision-making, the findings contribute to treatment personalization in adolescent ST and address key challenges such as suboptimal outcomes and treatment dropout. Moreover, the identified criteria provide a foundation for future quantitative validation.