In this randomized controlled trial, we will identify social networks on Facebook, an randomly assign each network to control or intervention status. We will then intervene at the level of the network with dynamic, interactive HIV prevention messages (intervention) or static messages about HIV prevention (control). We will develop the intervention content with input from our target audience (Facebook users) and will measure baseline, and 3 and 6 month assessments of condom use and abstinence among all participants