Unpacking the Black Box of Problem-Solving: Dosage, Delivery, Culture, and Impact on Internalizing Problems for Adolescents - Abstract Approximately 20% of young people experience anxiety or depression by the time they turn 18, and rates are higher among racial/ethnic minority youth. Improvement in problem-solving skills reduces depression, anxiety, self-harm, and suicidal ideation, and corresponds to reduced symptoms and better adjustment for youth with externalizing problems, pointing to its transdiagnostic potential. Problem-Solving Skills Training (PSST) is consistently revealed to be the most common element across youth mental health prevention and promotion programs; however, dosage and delivery vary - including the extent to which quantity, sequencing, temporality, steps and strategies account for its transdiagnostic value and impact. Additionally, despite long- standing psychotherapy literature documenting that cultural adaptation and tailoring predict engagement, alliance, and outcomes for racial/ethnic minority youth and families, the prevention literature has been slower to examine to what extent programs are designed with cultural diversity or specific groups in mind; delivered in culturally congruent ways; and to what extent these lead to better outcomes. As a result, the field’s readiness to disseminate evidence-based recommendations for maximum impact is limited. We have assembled an Advisory Board of scientific and community experts to inform two aims. Specific Aims 1: Examine PSST for variability in dosage, delivery, and cultural considerations, and variance in internalizing outcome effect sizes. We will (a) identify universal and selected prevention programs (n=~90) for adolescents (ages 14-18) outperforming a comparison in at least one trial on at least one internalizing outcome; (b) code dosage (quantity, sequencing, temporality), delivery (steps and strategies), cultural content and tailoring, and impact and (c) use random effects meta-regression to examine variance accounted for in problem solving skills and internalizing outcomes. Findings will inform Specific Aim 2: Develop, assess, and deploy a best practice PSST resource guide (TIPS = Teach It Plain & Simple) for youth service providers. We will recruit frontline providers (n=15, ~30% non-Hispanic Black, ~70% Hispanic) from three youth service settings (5 high school counselors, 5 middle/high afterschool professionals, 5 community health workers) to receive, review and integrate TIPS into their work. Two months later, we will receive feedback via surveys and semi-structured interviews in a sequential mixed method design, and conduct thematic analysis to assess usability, appropriateness, acceptability and feasibility. Findings will inform modifications to design for wider dissemination and an R01 application. Aligned with Strategic Plan Objective 4.2.C, the planned design allows for rapid infusion of research findings into practice settings for underserved communities to increase the impact of mental health interventions. By unpacking the black box of PSST, we hope to speed its scale-up as an efficient, effective, stand-alone, culturally congruent brief intervention tool for youth service providers in a variety of settings.