Characteristics of the social and physical environment — the social ecology — can positively or negatively influence the health and well-being of adolescents, including their ability to avoid contracting HIV and other diseases. This environmental/structural view suggests that risk for disease cannot be solely explained by characteristics of individuals, such as knowledge of HIV transmission or attitudes towards risky sexual behavior. The broader social ecology — from micro-level influences such as household resources, neighborhood disorder, and social networks to macro-level factors such as laws and policies — can restrict or enhance individual agency to avoid risk. Thus in developing prevention interventions, it is necessary to understand and address social-ecological factors that influence health in a particular context. This paper will examine the use participatory mapping and geospatial technologies to understand the context of disease and to inform the development of a setting-level HIV prevention intervention in Muhuru Bay, a small fishing village on the shore of Lake Victoria in western Kenya.