PROJECT SUMMARY/ABSTRACT This proposal seeks to investigate how social relationships (including social support, social integration, and negative interpersonal interactions) impact behavioral health treatment-seeking among post-Maria Puerto Rican migrants. Puerto Ricans are the second-largest Latinx group in the United States (US) and have the highest rates of behavioral health (BH) disorders among Latinx heritage groups. There is evidence that this may be due to the circular migration patterns that result from Puerto Ricans having US citizenship, which entails frequent disruptions to social networks. At the same time, Latinxs utilize BH services at lower rates than non-Latinxs, suggested a significant unmet treatment need. This study will investigate how the social relationships of post-Maria Puerto Rican migrants 1) influence perceived need for treatment and 2) influence service utilization. The results of the study can be used to inform culturally-congruent outreach efforts and BH services and suggest routes to reduce future BH treatment gaps with Latinx (im)migrant populations. The proposed study will have both quantitative and qualitative components. It will use prospective survey data from the parent study – the Adelante Boricua project – to determine salient social relationship influences on BH treatment outcomes. Qualitative interviews conducted for the proposed study will then explore in depth the associations between social relationships and BH treatment outcomes found in the quantitative aims. In addition to the proposed study, the training plan for this fellowship will provide a variety of opportunities to develop as a well-rounded, community-engaged health services researcher. These opportunities include advanced coursework to develop substantive and methodological knowledge, interdisciplinary team-based research experience, and mentored practice in working effectively with community advisory boards. The sponsor and co-sponsor both have extensive expertise with Latinx populations, including behavioral health (sponsor) and systems navigation (co-sponsor). They are supported by the institutional environment of the Boston College School of Social Work, which has a cadre of researchers who focus on Latinx and immigrant populations and a wealth of resources for conducted community-engaged research. The sponsorship team and institutional environment are ideal for completing the proposed study and training plan for this fellowship.