A Hybrid Type 1 Effectiveness-Implementation Trial of a Digital Health Intervention for Youth in Out-of-Home Care - PROJECT SUMMARY Youth in out-of-home care (OOHC; e.g., youth in foster care, group homes) face significant health disparities in three interrelated areas of adolescent development: sexual health, mental health, and relationship health. These health concerns co-occur and reinforce one another – for example – A confluence of factors including an adolescent developmental phase marked by risk taking and exploration, adverse childhood experiences, unstable familial relationships, and fragmented health education and services contribute to these significant health disparities. D depression is associated with decreased condom use among adolescents. igital health interventions (DHIs) have successfully addressed various health issues among other marginalized populations, offering an innovative yet untested platform for delivering comprehensive health and wellbeing services to youth in OOHC. The proposed research will develop a DHI called BeYouConnect (BYC) to improve the health of youth in OOHC and evaluate BYC in a hybrid type 1 effectiveness-implementation study. The development, implementation, and evaluation of BYC will be guided by the RE-AIM framework and the intervention will be delivered via the evidence-based HealthMpowerment platform. Co-production methods will be employed, Aim 1 (K99) will involve developing BYC, a DHI that addresses sexual health, relationship health, and mental health for youth in OOHC. In two design labs with OOHC youth (n=12-15 each), sexual and relationship health content will be adapted from an existing evidence-based program, HEART, for delivery via app and mental health content will be co-created with youth. Aim 2 (K99) will beta-test BYC to assess feasibility and acceptability (n=25 OOHC youth). Aim 3 (R00) will evaluate BYC in a 6-month hybrid type 1 effectiveness- implementation trial (n=186 OOHC youth). The research plan is complemented by a training plan that builds on the candidate's strong applied research experience at the intersection of public health and psychology and includes four training objectives: including the creation of a Youth Collective (n=10) to provide input and guidance on the research aims. 1) Advance knowledge in developing interactive, tailored DHIs; 2) Develop expertise in analyzing backend paradata to assess feasibility, acceptability, and effectiveness of DHIs 3) Gain expertise in implementation science frameworks and hybrid effectiveness-implementation designs, including in digital health settings; and 4) Engage in professional development necessary to transition from a mentored postdoctoral fellow into a fully independent research scientist. An exceptional mentoring team of experts in DHIs, implementation science, paradata analytics, and community-engaged research - including Drs. Kate Muessig, José Bauermeister, and Henna Budhwani, alongside Scientific Advisors, Drs. Lisa Hightow-Weidman and Laura Widman - will support the applicant in achieving these research and training goals. This K99/R00 proposal will position the applicant to launch an independent career in behavioral DHIs, leading innovative research that advances the field, ultimately improving the health of marginalized youth.