With nearly 50 million children under 5 years of age wasted, more research is needed on effective interventions. To help identify and prioritize the most important outstanding research questions in this area, the authors conducted a research prioritization exercise using the “Child Health and Nutrition Research Initiative” method. They compiled lists of research gaps from multiple sources, categorized them into themes, and used an expert group to identify and rank the 40 most critical questions. The study concluded that research is most needed on 1) how the pathways to wasting encompass the in-utero environment, 2) wasting and early infancy, 3) the early identification of wasting, and 4) the most effective wasting interventions.