Project Summary Youth in the child welfare system have documented high rates of mental health symptoms and experience significant disparities in mental health care services access and engagement relative to youth not in the child welfare system. Navigator models have been developed in the healthcare field to address challenges of service access, fragmentation and continuity that impact quality of care, but at present there is no empirically supported mental health navigator model to address the unique and complex mental health needs of child welfare involved (CWI) youth. This developmental study will be conducted in three phases consistent with study aims. The study will take a mixed-methods, multi-informant participatory research approach to developing, iteratively refining and pilot testing a Foster Care Family Navigator (FCFN) model to improve mental health service outcomes for adolescents (ages 12-17) involved in the child welfare system. The navigator model will leverage digital health technology to engage with and improve care coordination, tracking and monitoring of mental health service needs for these youth and families. The study will adapt the JJ- TRIALS Behavioral Health Services Cascade framework to support a data-driven decision-making approach to improving identification of mental health service needs and outcomes. The study will first utilize a combination of interagency collaborative meetings, youth and family focus groups and qualitative individual interviews with multisystem stakeholders to guide the development of the FCFN protocol. Next an open trial of the 6-month FCFN intervention will be conducted and the protocol iteratively refined through direct participant feedback. The last phase of the study will focus on conducting a modified roll-out design of the FCFN intervention with 75 child welfare involved youth. Three cohorts of 25 youth and caregivers each will receive FCFN services for 6 months and will be compared on primary outcomes of mental health initiation and engagement to 50 youth and caregivers who receive services as usual. We will explore mediators (e.g., satisfaction with navigator, youth treatment motivation, perceived barriers to care) and moderators (e.g., race, ethnicity, sex) of intervention impact to inform intervention mechanisms of change and key demographic and other contextual factors associated with trial outcomes. Finally, we will also conduct qualitative exit interviews with trial participants and navigators to gain a deeper understanding of influences on pilot outcomes that can inform future larger efficacy and effectiveness trials.