Integration of a Culturally Responsive Family Peer Delivered Engagement Strategy in Coordinated Specialty Care - ABSTRACT Family member/support person engagement in mental health services has known benefits such as continuous engagement, medication adherence, and improved quality of life among service users in the early stages of psychosis. As such, early intervention services in the form of coordinated specialty care models include family psychoeducation, an evidenced-based intervention. Despite the known benefit of family engagement less than 50% of family members engage in coordinated specialty care and even lower rates have been reported among diverse families (e.g., ethnoracially minoritized, low socioeconomic), fueling disparities in service utilization. To address this, we piloted and established the acceptability and feasibility of a family peer delivered FAMily Engagement Strategy (FAMES), aimed at providing culturally responsive care to improve family member engagement throughout coordinated specialty care and address disparities among historically underserved communities (e.g., ethnoracial minorities, rural residents). Informed by the Health Equity Implementation Framework, we propose to conduct a Hybrid Type 1 Effectiveness-Implementation designed trial, to examine the effectiveness and evaluate the implementation of family peer delivered FAMES in eight coordinated specialty care programs geographical distributed throughout the U.S. (New Mexico, Oregon, Tennessee, and Washington). The aims of the proposal are to: 1) Conduct a fully powered stepped-wedge clustered randomized trial with eight coordinated specialty care programs who will recruit 448 family member/support person and client participant dyads to determine whether integrating FAMES improves engagement compared to attention control; 2) Examine mechanisms of change (self-efficacy, connectedness, motivation) and equity-related moderators defined by key determinants (e.g., race, ethnicity, gender identity, individual and neighborhood socioeconomic status, rural-urban) on treatment effects; and 3) Guided by RE-AIM, evaluate the implementation (reach, adoption, implementation fidelity, and sustainability) of FAMES using a rigorous mixed methods approach that includes 68 semi-structured interviews as part of a longitudinal qualitative component with family peers and CSC team members. This project aligns with NIMH’s Strategic Plan and commitment to advancing equity in mental health services.