Suicide is the second leading cause of death in youth, and the latest statistics indicate disproportionate risk for suicidal behavior among Black youth.2. Unfortunately, few interventions effectively prevent youth suicidal thoughts and behaviors (STBs). Experts emphasize that ideal foci for effective STB prevention interventions are proximal, robust and modifiable, with broad acceptability and accessibility for population-level impact. Sleep difficulties may be a particularly promising target for youth STB prevention efforts. Studies consistently demonstrate a direct and temporal link between sleep disturbances in adolescents and STBs and are included among the expert consensus set of warning signs for suicide. Furthermore, gross disparities in sleep between Black youth and their White peers (e.g., shorter sleep duration, poorer sleep quality, more variable sleep timing), as well as unique and specific barriers to healthy sleep for Black youth (e.g., racial discrimination) are directly linked to elevated risk for depression and STBs. Yet, no intervention targeting sleep difficulties has been examined among youth at-risk for STBs nor tailored to Black youth. We posit a modularized intervention that targets a range of sleep and circadian difficulties using evidence-based principles, such as the Transdiagnostic Sleep and Circadian Intervention (TSC), holds promise to decrease risk for STBs in depressed adolescents. To optimize TSC acceptability, engagement, and scalability for youth at-risk for STBs, including Black youth, among whom mental health services are more stigmatized, we will employ the health equity-informed framework, and draw upon the expertise in implementation science and qualitative methods among our team and the larger Center. We will apply the Consolidated Framework for Implementation Research (CFIR) in conducting focus groups with youth, caregivers and providers to inform TSC implementation with depressed adolescents, including Black youth, and then evaluate these strategies through rapid iterative pilots. We will then conduct a randomized trial of 75 at-risk youth age 12-18 (35% Black) with moderate depression and clinically significant sleep difficulties identified in pediatric primary care via the Signature R01. Youth will be randomized using 2:1 allocation (to maximize data on implementation) to TSC+Sleep Feedback (i.e., user-friendly graphical representations of naturalistic objective and subjective sleep data) or Sleep Feedback Only. All participants will complete objective ambulatory sleep assessment (via wrist-worn actigraph) and subjective daily sleep diary data (via smartphone), and receive weekly reports summarizing their sleep (Sleep Feedback). TSC clinicians will personalize TSC strategies through use of the adolescent’s Sleep Feedback data. We will examine TSC feasibility, acceptability and impact on sleep; secondary outcomes include depression and STB risk, assessed at 1,3, and 6 months. Resultant data supporting promise of TSC will inform a larger randomized trial. This intervention has the potential to advance health equity by addressing one potential source contributing to disparities in STB in Black youth.