Project Summary/Abstract Social-structural forces - poverty, stigma, racism, and gender inequality - have exacerbated HIV disparities for key populations around the world and particularly in sub-Saharan Africa. As the world moves towards the 90- 90-90 HIV cascade of care goals, in which 90% of individuals living with HIV know their status, 90% of these are linked to care, and 90% of those engaged in care are virally suppressed, the same social-structural forces are likely to push key populations disproportionately into the 10% left behind at each step of the care cascade. Structural interventions that address multiple levels of the social ecology and empower communities to dismantle social and institutional barriers can improve cascade of care outcomes and decrease incidence among key populations. The complexity of these interventions contributes to their success, but also presents a methodological challenge to assess the mechanisms through which they simultaneously create change at individual, community, and institutional levels. This K01 Mentored Research Scientist Career Development Award is designed to provide the PI with training in a mixture of qualitative, quantitative, and geospatial methods to address this challenge. The proposed research will explore how social-structural forces influence the spaces where high risk women in Iringa, Tanzania live, work, and access health care, and how these spaces affect access to HIV testing and linkage to care. This work will build the PI’s skills in 1) Qualitative and quantitative geographic information systems; 2) Latent class analysis with an emphasis on spatial factors; and 3) The design and implementation of community-based social-structural interventions. The project will be nested within an existing NIMH-funded R01 community-based intervention with high-risk women. The research aims are to: 1) Identify spatial clusters of work venues and residential areas in which women are significantly more or less likely to access HIV testing or be linked to care; 2) Use latent class analysis to identify patterns of spatial use, the characteristics of women who are most likely to frequent those spaces, and differences in HIV testing and linkage to care by latent spatial class; and 3) Describe the spatial manifestations of social-structural forces that create barriers to HIV testing and linkage to care from the perspective of local women and identify how these correlate with spatial patterns identified in the first 2 aims. Findings from this study will position the PI to develop an R34 proposal for a geographically targeted and spatially tailored pilot intervention to improve cascade of care outcomes and reduce HIV incidence. The skills gained will allow the PI to transition to independence as an expert in community-based, mixed-methods research and interventions to reduce HIV disparities among key populations.