PROJECT SUMMARY The goal of this study is to test a multilevel approach to reduce adverse consequences of the COVID-19 pandemic with disparate impacts on Latinx and Black immigrants and refugees by observing and implementing three nested levels of intervention: 1) an efficacious 6-month peer advocacy and mutual learning model (Refugee and Immigrant Well-being Project, RIWP); 2) engagement with community-based organizations (CBOs); and 3) structural policy changes expected to be enacted in response to the pandemic, such as a state disaster relief proposal for mixed status Latinx families and expanded statewide health insurance coverage. This community-based participatory research (CBPR) study builds on a long-standing collaboration with five community-based organizations (CBOs) that focus on mental health, education, legal issues, and system change efforts to improve the well-being of Latinx immigrants and African refugees. By including 240 Latinx immigrants and 60 African refugees recruited from CBO partners who are randomly assigned to treatment-as- usual CBO involvement or the RIWP intervention and a random sample comparison group of 300 Latinx immigrants, this mixed methods longitudinal waitlist control group design study with seven time points over 36 months will test the effectiveness of the RIWP intervention and engagement with CBOs to reduce psychological distress, daily stressors, and economic precarity and increase protective factors (social support, critical awareness of/access to resources, English proficiency, cultural connectedness, and mental health service use). This study will also test the ability of the RIWP intervention and engagement with CBOs to increase access to the direct benefits of structural interventions (local/state relief-related policies) for Latinx and Black immigrants and refugees. Mechanisms of intervention effectiveness will be explored by testing mediating relationships between primary outcomes and protective factors. We will also track local/state policy changes and obtain preliminary quantitative estimates of effects of these structural interventions on psychological distress, stressors, and economic precarity using propensity score matching. Qualitative interview data from a purposive subsample of participants and CBO staff will enable additional exploration of mechanisms of change, the effects of policy interventions on individuals, how CBOs contribute to enacting policies and helping people benefit from them, and the context of RIWP implementation at each site. This research is innovative and significant because it employs cutting-edge research design and intervention strategies to advance the science of multilevel mental health interventions that aim to understand and address underlying structural inequities and resulting mental health disparities that have been highlighted and exacerbated by the pandemic. Thus, this study will contribute not only to reducing the disparate adverse mental health, behavioral, and socioeconomic consequences of the COVID-19 pandemic but also to our ability to eliminate mental health disparities among Latinx and Black populations.