The FOAM (Focus on Opportunity, Ability, and Motivation) is a framework designed to help in the development, monitoring, and evaluation of handwashing behavior change programs. FOAM was developed for use in resource-poor settings, but it can also be adapted for other socioeconomic environments. This working paper is intended for use by program managers implementing handwashing behavior change initiatives, as well as multilateral and bilateral agencies, academic institutions, and government and nongovernmental organizations (NGOs) working in water and sanitation.