Hand washing with soap is the most effective and inexpensive way to prevent diarrheal and acute respiratory infections, which take the lives of millions of children in developing countries every year. Together, they are responsible for the majority of all child deaths. Yet, despite its lifesaving potential, hand washing with soap is seldom practiced and difficult to promote.

The challenge is to transform hand washing with soap from an abstract good idea into an automatic behavior performed in homes, schools, and communities worldwide. Turning hand washing with soap before eating and after using the toilet into an ingrained habit could save more lives than any single vaccine or medical intervention, cutting deaths from diarrhea by almost half and deaths from acute respiratory infections by one-quarter. A vast change in hand washing behavior is critical to meeting the Millennium Development Goal of reducing deaths among children under the age of five by two-thirds by 2015.