Nearly half of men who have sex with men (MSM) men experience adult sexual assault (ASA) in their lifetime. Rates of ASA MSM are alarmingly high even when measured over short periods of time. However, little research has examined risk and protective factors for ASA among MSM. Research that does exist is mostly cross-sectional or focuses on sexual partner aggression rather than ASA across a broad range of relationships (e.g., acquaintances, coworkers). The lack of research on ASA among MSM precludes researchers and practitioners from developing prevention programming. There is also a dearth of research on factors that predict negative outcomes associated with ASA among MSM, and factors that may buffer against negative outcomes. The purpose of the proposed study is to utilize a longitudinal, prospective design to test innovative models that include factors (e.g., child abuse, alcohol use) to better understand risk for (Aim 1) and outcomes of ASA (Aim 2) among MSM. We will also examine how personal and stressful experiences relate to one another (Aim 3) and how these experiences predict and moderate models examined in Aims 1 and 2. We will include MSM regardless of their relationship status since ASA can occur in various types of relationships (e.g., serious relationships, acquaintances). The methodology includes recruiting MSM (N = ~3,600) via multiple methods (e.g., fliers, social media, snowball sampling). Participants will complete online surveys at 0-, 6-, 12-, 18, and 24- months. The proposed project will provide critically important information that will inform the immediate development of prevention and intervention efforts for MSM, ultimately reducing costs to American society.