PROJECT ABSTRACT The current proposal addresses the relationship between interpersonal emotion regulation and suicide in Nepali youth. Despite the disproportionately high suicide burden in low- and middle-income countries (LMIC), the global mental health field has made limited progress in predicting and preventing youth suicide. Interpersonal factors are strongly and consistently linked to youth suicide in LMIC. However, the pathways through which interpersonal factors influence suicidal behaviors in LMIC are unclear and represent a critical gap in youth suicide prevention. Emotion regulation may provide a promising bridge between interpersonal factors and suicide in LMIC. However, current emotion regulation in LMIC is negligible and limited in its focus on the individual at the expense of the broader social and cultural context in which emotion regulation occurs. The current mixed-methods study leverages advances in clinical behavioral science and dynamic systems modeling to investigate interpersonal emotion regulation processes in Nepali youth with rapidly rising rates of suicide. The study focuses on expressive suppression (ES), an interpersonal emotion regulation mechanism with salient cultural dimensions. In this sequential exploratory study, the study aims to: (1) use qualitative methods to identify culturally-relevant behavioral indicators of ES in Nepali youth; and (2) use these indicators to code for ES during a structured laboratory observation between Nepali youth dyads that explores dynamic associations between ES and interpersonal validation, negative emotion, and suicidal behaviors. By providing a dynamic understanding of real-time interpersonal processes implicated in suicide, findings can be used to develop culturally-relevant suicide interventions for in Nepal and other LMIC where the global suicide epidemic is concentrated. Findings can also generalize to Asian-American and Nepali-origin Bhutanese refugee youth in the U.S. with rapidly rising rates of suicide. A dynamic understanding of interpersonal processes suicide significantly improves our understanding of the Research Domain Criteria “Social communication” construct and can also be extended to other disorders (e.g., depression, anxiety, and post-traumatic stress) where interpersonal processes are also central. The applicant is ideally positioned to conduct this work given her strong global mental health research and publishing background, six-year history conducting suicide and emotion regulation research in Nepal, well-situated mentorship team of relevant content and methodological experts, and access to required resources and mentorship in Nepal.