The overall purpose of the ImpactEvaluation is to provide decision makers with a body ofrigorous evidence on the effects of the hand washing andsanitation projects at scale on a set of relevant outcomes.It also aims to generate robust evidence on a cross-countrybasis, understanding how effects vary according to eachcountry's programmatic and geographic contexts, andgenerate knowledge of relevant impacts such as childcognitive development, child growth (anthropometric)measures, anemia, acute lower respiratory disease, andproductivity of mother's time, among many others. Thestudies will provide a better understanding of at-scalesanitation and hygiene interventions. The improved evidencewill support development of large-scale policies andprograms, and will inform donors and policy makers on theeffectiveness and potential of the Global Scaling Upprojects as massive interventions to meet global needs.