Monitoring hand hygiene adherence and providing performance feedback to health care workers is a critical component of multimodal hand hygiene promotion programs, but important variations exist in the way adherence is measured. Within the framework of the World Health Organization's (WHO) First Global Patient Safety Challenge known as "Clean Care is Safer Care," an evidence-based, user-centered concept, "My five moments for hand hygiene," has been developed for measuring, teaching, and reporting hand hygiene adherence. This concept is an integral part of the WHO's hand hygiene improvement strategy conceived to translate the WHO Guidelines on Hand Hygiene in Health Care into practice. It has been tested in numerous health care facilities worldwide to ensure its applicability and adaptability to all settings irrespective of the resources available. Here we describe the WHO hand hygiene observation method in detail-the concept, the profile and the task of the observers, their training and validation, the data collection form, the scope, the selection of the observed staff, and the observation sessions-with the objective of making it accessible for universal use. Sample size estimates, survey analysis and report, and major bias and confounding factors associated with observation are discussed.