This study suggests that mass-media-generated interpersonal communication networks vary according to an individual's behavior-change stage. As people in Peru adopted modern family planning methods, they increasingly formed and perhaps relied on information from more technical interpersonal communication networks, which shifted from peers to doctors and other service providers. Moreover, information seeking and giving varied with adoption stages in unexpected ways. In collaboration with Apoyo a Programmas de Población (Advocacy for Population Programs) of Peru, we present a model of how interpersonal communication networks generated by mass media messages vary with stage of behavior change.