Medical discourse has long dominated research and policy design targeting commercial sex workers in efforts of HIV prevention. Such an approach has generated solutions to the problem of disease transmission conceptualized in terms of individual knowledge and behavior rather than the broader ecology of social, economic, and political forces driving risky behavior within sex work. These ecological forces faced by sex workers include poverty, physical abuse, lack of legal protection, and stigmatization. Ignoring these forces leads to two types of problems for the design of policy solutions. First, policies that ignore the ecological forces of commercial sex work will misconstrue the pathways to risky sexual behavior and thus jeopardize the effectiveness of diseasecontrol efforts. Second and related, those policies will neglect the gaping welfare deficiencies sex workers face, which demonstrates the failure to safeguard sex workers’ basic human rights. This thesis investigates the ecological risk forces of 99 female sex workers in rural Kenya through qualitative and quantitative interviews. A rich tableau of their quotidian and long-term challenges depicts the micro-level forces and the larger structures of inequality driving sex workers’ behavior. It supports the main argument of this thesis, that consideration of ecological forces must be central to the design of policies and interventions to increase disease-control efficacy and to realize sex workers’ basic human rights