PROJECT ABSTRACT The experience of hematopoietic cell transplantation (HCT) for hematologic malignancy among Adolescents and Young Adults (AYAs) is particularly difficult because age-related developmental challenges of identity, relationships, and vocation may add to the burden of cancer. Compared to other age-groups, AYAs have poorer psychosocial outcomes including increased anxiety and depression and poorer adherence to oral immunosuppressive medications potentially predisposing AYAS to disease-related morbidity and and/or cancer-relapse. A potential barrier to improving these experiences may be that AYAs have few opportunities to develop the personal resources needed to handle adversity. We have previously developed the “Promoting Resilience in Stress Management” (PRISM) intervention for AYAs with serious illness. This manualized, brief intervention is delivered in 4, 30-60-minute, one-on-one sessions, followed by a Parent/ Caregiver/ Spouse/ significant other inclusive meeting. It targets skills in stress-management and mindfulness, goal-setting, positive reframing, and meaning-making. Findings from a phase 2 randomized controlled trial among AYAs with newly diagnosed cancer demonstrate that PRISM is associated with decreased psychological distress and increased health-related quality of life. This study will build on our prior experience and fill a critical knowledge gap regarding PRISM’s impact among AYAs receiving HCT. Thus, we will conduct a multi-site randomized controlled trial among N=70 AYAs (n=35 PRISM and n=35 usual care; ages 12-24 years), with the primary trial outcome of patient-reported symptoms of anxiety and depression. We hypothesize that AYAs who receive PRISM will report fewer mixed affective symptoms, demonstrate better adherence, and show improved biomedical outcomes, while their parents report improved quality of life and psychological distress. This study offers an opportunity to expand the body of knowledge regarding methodologically rigorous and evidence- based psychosocial interventions and standards of care for AYAs with hematologic malignancies and has the potential to reduce the burden of cancer in these vulnerable populations. In this proposed diversity supplement, I will contribute to evaluating PRISM’s efficacy in reducing symptoms of anxiety and depression over the first 6-months post-HCT by assisting with procedure related to recruitment, data collection, and analysis.