This lecture will discuss strategies to address the challenges of marketing new products and behaviors to poor consumers in emerging markets. Disseminating new products and creating new markets in developing nations is complicated by (a) behavioral aversions to new technologies and new products, and (b) institutional and structural deficiencies that create market failures. We will outline economic models of various impediments to behavior change and then delve into one field project in which we use a series of randomized controlled trials to understand the marketing challenge for a specific product, and how to overcome it.