PROJECT SUMMARY/ABSTRACT In recent years, the prevalence of suicidal ideation among young Black and Latinx individuals has been on the rise1,2,3 with racial/ethnic discrimination and adverse childhood events (ACEs)4,5 thought to explain this health disparity. Systemic inflammation?a product of over-activation of the body?s stress response system?has been hypothesized to play a unique predictive role in suicidal ideation development6,7,8. Experiencing racial/ethnic discrimination and ACEs can lead to systemic inflammation9,10,11?possibly accounting for suicidal ideation?s growing prevalence among young racial/ethnic minorities who experience ACEs and discrimination at disproportionate rates. Conversely, secure attachment relationships have been associated with a reduction in systemic inflammation12 and a lower risk for suicidal ideation13. The broad aim of this fellowship research is to test biological and relational mechanisms explaining suicidal ideation among racial/ethnic minority young adults, specifically examining ACEs and racial/ethnic discrimination as risk factors as well as the mediating role of systemic inflammation and the protective effects of close relationships. Chronic exposure to racial/ethnic discrimination and ACEs can lead to dysregulation of the hypothalamic- pituitary-adrenal (HPA) axis, leading to an exhausted release of proinflammatory cytokines and systemic inflammation10,14,15. Biological models identify systemic inflammation as a potential mediator of suicidal ideation given elevated levels of proinflammatory cytokines in individuals with suicidal behaviors6,8,9 Further, studies have shown ACEs and racial/ethnic discrimination can alter proinflammatory cytokine levels and signaling10,15 However, no study has attempted to investigate systemic inflammation as a mediator of suicidal ideation in adulthood nor the proposed risk or protective factors within this pathway. This proposal addresses these gaps by (a) examining whether the links between ACEs and racial/ethnic discrimination with suicidal ideation are mediated by systemic inflammation and (b) examining attachment security as a moderator. This proposal utilizes a biopsychosocial model integrating multiple levels of analysis (i.e., immunobiological, behavioral, relational). It reflects the mission of the National Institute of Minority Health and Health Disparities (NIMHD) to identify mechanisms and protective factors of disparities such that this study aims to elucidate how systemic inflammation might arise from ACEs and racial/ethnic discrimination and increase risk for suicidal ideation in young adults with emphasis on the protective effects of secure attachment relationships to uncover fundamental mechanisms of a pressing health disparity in diverse populations. Finally, this award will aid in training a young researcher seeking to understand the mechanisms associated with negative outcomes in young adults from ethnic/racial minority groups by providing necessary scaffolding toward an independent research career and opportunities for advanced research skills breadth depth of knowledge across disciplines.