This article was part of a special supplement in the Food and Nutrition Bulletin on the Alive & Thrive (A&T) project. Global interest in scaling up nutrition outcomes has focused attention on the need for more effective programs to improve infant and young child feeding (IYCF). However there are few examples in the literature of comprehensive programs that have been systematically designed. Behavior change principles, epidemiological data, situational analysis, stakeholder consultations, formative research, and feasibility studies informed the design of IYCF programs delivered at scale in Bangladesh, Ethiopia, and Viet Nam.