Understanding the interplay between interpersonal communication and health campaigns is important for campaign planners and evaluators because campaigns do not operate in a vacuum with messages flowing directly from media to audiences and affecting attitudes, beliefs, intentions, and behaviors. Instead, campaign messages encounter contextual factors, such as everyday talk between people, which operate outside a campaign's control. Interpersonal communication can extend campaign reach and amplify or dampen campaign messages.

Early communication hypotheses, including Elihu Katz and Paul Lazarsfield's two-step flow process and Everett Rogers's diffusion of innovations model, highlighted the importance of interpersonal communication in disseminating campaign information through social networks. More recently, researchers such as Brian Southwell and Marco Yzer have examined factors that determine how and when health campaigns stimulate interpersonal communication and the ...