To test the efficacy of a sustainable community-level HIV intervention among sex workers, the Sonagachi Project was replicated, including community organizing and advocacy, peer education, condom social marketing, and establishment of a health clinic. Sex workers were randomly selected in 2 small urban communities in northeastern India (n = 100 each) and assessed every 5-6 months over 15 months (85% retention). Overall condom use increased significantly in the intervention community (39%) compared with the control community (11%), and the proportion of consistent condom users increased 25% in the intervention community compared with a 16% decrease in the control community. This study supports the efficacy of the Sonagachi model intervention in increasing condom use and maintaining low HIV prevalence among sex workers.