ABSTRACT African Americans living with chronic health conditions are more likely to experience depression and other mental health disorders than their healthy counterparts, and are more likely to experience severe depression than whites, but less likely to be diagnosed or receive treatment. One especially vulnerable group is patients with sickle cell disease (SCD), a genetic blood disorder that primarily affects people of African descent, many of whom live in disadvantaged circumstances and are cared for in under-resourced settings. SCD causes severe acute and chronic pain, end-organ damage, and early mortality. Patients transitioning from adolescence to adulthood (ages 16-30) are at high risk for mental health disorders and suicide. Using mobile technology, we can provide high-quality, evidence-based behavioral mental health treatment that reaches patients in different settings. Digital cognitive behavioral therapy (CBT) is effective for treating depression and anxiety and can be brought to scale at low cost. Despite the promise of digital CBT, there are barriers to its widespread use, particularly in low-resource settings serving minorities. Qualitative data show that cultural factors—lack of relatability, representation, and perceived stigma regarding mental health treatment—limit engagement with digital CBT programs. Population- and setting-specific adaptations to interventions can lead to their successful implementation and wider use. We will work with a digital CBT program to decrease stigma and make it more relatable and relevant to young adults with SCD, by devising changes to advertising and promotion, and tailoring communication with an integrated health coach, Aim 1: Use implementation science (ImS) and human-centered design methods to define the barriers to delivering routine mental health screening and digital CBT to adolescents and young adults with SCD. Aim 2: Rapidly iterate, test, and evaluate adaptations to the implementation strategy for a coach-enhanced digital mental health service. Aim 3: Demonstrate that a population-specific implementation strategy improves engagement with a digital CBT-based mental health service. We will capitalize on our mobile technology tools, interdisciplinary expertise, and community-based partnerships to investigate the implementation of digital CBT into low-resource clinics and community-based organizations serving adolescents and adults with sickle cell disease. This study will generate the necessary data and infrastructure to conduct a large scale, R01-funded, multi-site pragmatic trial to determine how digital CBT can be used as an effective, low-cost, and scalable mental health treatment for adolescents and young adults with SCD, and that will be generalizable to other underserved, depressed populations with chronic pain syndromes. 1