RESEARCH ARTICLE Is Scale-Up of Community Mobilisation among Sex Workers Really Possible in Complex Urban Environments? The Case of

Background In the last decade, community mobilisation (CM) interventions targeting female sex workers (FSWs) have been scaled-up in India’s national response to the HIV epidemic. This includ-ed the Bill and Melinda Gates Foundation’s Avahan programme which adopted a business approach to plan and manage implementation at scale. With the focus of evaluation efforts on measuring effectiveness and health impacts there has been little analysis thus far of the interaction of the CM interventions with the sex work industry in complex urban environments. Methods and Findings Between March and July 2012 semi-structured, in-depth interviews and focus group discus-sions were conducted with 63 HIV intervention implementers, to explore challenges of HIV prevention among FSWs in Mumbai. A thematic analysis identified contextual factors that impact CM implementation. Large-scale interventions are not only impacted by, but were shown to shape the dynamic social context. Registration practices and programme monitor