Advocates of promoting handwashing withsoap agree that this behavior has important health benefitsacross the globe. Efforts, both large-scale and focused, areunderway worldwide to promote handwashing with soap at thecommunity level (www.globalhandwashing.org). Although thereis broad agreement about the health benefits of promotinghandwashing with soap, there is not similar agreement aboutthe best ways to measure the behavior that these promotionprograms set out to change. The reality is this: there is nouniversally applicable method for measuring handwashingbehavior that is valid, relevant, affordable, andlogistically feasible for the various settings in which suchbehavior might need to be measured. The aim of this documentis to describe techniques and to propose strategies formeasuring handwashing behavior for a variety of scenarios.