Project Summary/Abstract This K23 proposal is designed to help Dr. Pederson achieve her long-term goal of becoming an independent investigator with expertise in developing and testing interventions that reduce mental health stigma, increase engagement in mental health services, and improve mental health outcomes. The candidate and her mentors have developed a comprehensive training plan: 1) to build her expertise in user-centered design and digital mental health intervention development, so that she can engage end-users early in the intervention design process both in this study and in future trials; 2) to expand her training in community engaged research to address health disparities and promote engagement in mental health services; and 3) to bolster her skills in the conduct of clinical trials and quantitative analysis of clinical trial data for a future R01 application centered on implementing and testing a fully powered anti-stigma contact intervention. The efficacy and precision of anti- stigma interventions to improve mental health outcomes among underserved Black adults are grossly limited and represent a critical public health gap. Studies show stigma compounds disabilities related to the primary symptoms of mental illness, and increases morbidity and premature mortality related to mental illness. Compared with white adults, Black adults with mental illness have more chronic disease, and more severe illness at presentation. Meta-analyses have consistently shown that both face-to-face and video based contact with individuals with mental illness can reduce stigma. Recent studies that distinguished contact delivery showed effect size for video-based contact to be comparable to face-to-face contact. Digital mental health also offers a platform to overcome barriers to early access, implementation, and scalability. Strong preliminary data identify mental illness stigma and medical mistrust as critical intervention targets that should be addressed in order to increase mental health service utilization among Black adults. To address these gaps in the literature, the following specific aims are proposed: 1) a user-centered design approach will be used to develop a self- administered, video-based mobile app to reduce stigma and medical mistrust among Black adults; 2) a pilot randomized trial design will be used to assess the feasibility and acceptability, and test the preliminary efficacy, of a self-administered, video-based mobile app in reducing mental illness stigma among Black adults with moderate to severe depression or anxiety; and 3) a causal mediation analysis will be used to estimate the extent to which changes in anticipated/enacted/internalized stigma and medical mistrust mediate the intervention’s effect on the primary and secondary outcomes. The key innovation of this proposal is that it will be the first mobile health intervention focused on mental health stigma reduction using a targeted approach by integrating user characteristics (...