PROJECT SUMMARY Black women (BW) in the US are disproportionately affected by HIV. Concurrently, Black women face sociostructural inequities including structural racism, HIV stigma, and medical mistrust, in addition to the syndemic effects of substance use, and intimate partner violence, and adverse mental health. These factors act as barriers to health seeking behaviors that contribute to poor HIV outcomes. BW’s participation in HIV clinical research remains historically low and BW’s participation in HIV research (i.e., prevention, treatment, cure), which remains historically low, is contextualized within a system that does not consider their intersectional identities (i.e., race, gender), while routinely excluding women due to biological (e.g., reproductive potential, menstruation, pregnancy), social (e.g., restrictive contraception requirements, provider bias, perceived as “hard to reach”), and structural factors (e.g., lack of welcoming research spaces including extended hours and childcare support). While studies have identified factors that limit women’s participation in HIV research, there is limited data on perceptions of HIV research participation among BW. The prevalence of illicit substance use (e.g., cocaine, amphetamines) among Black women is higher than the national average. Consequently, there is a significant risk of BW not benefitting from HIV related scientific advances (i.e., access to HIV medications, curative therapies) derived from research. Guided by syndemic theory and intersectionality framework, this explanatory sequential mixed methods study will utilize a case control approach to elucidate the effects of sociostructural inequities and past-year substance use, and past-year intimate partner violence, and adverse mental health on participation in HIV research among BW (Aim 1). For the case-control portion of the study, we will recruit, screen, and match participants 1:1 across case and control groups (n=280, cases (n=140): participated in research; controls (n=140): not yet participated in HIV research) along factors of (a) HIV serostatus and (b) recruitment source (sociobehavioral, clinical, vaccine, biomedical prevention study and non-research efforts. Understanding these effects on BW participation in HIV research may elucidate aspects for intervention (e.g., policy changes regarding stopping rules, minimum participant thresholds) to ensure more diverse study populations in HIV research. The proposed study will include three groups: a) BW enrolled in ongoing sociobehavioral research studies by members of the mentoring team, LinkPositively (R34MH122014; PI: Stockman) and Women Shine; (R01MH125785 PI Stockman) who agreed to be contacted about future research opportunities (n=40), b) BW with histories of research participation who agreed to be contacted about future research opportunities, and those seeking care at AIDS Clinical Trials Group clinical research sites without a history of research participation (n=65), c) p...