Researchers at the Emory Rollins School of Public Health, in collaboration with the WHO, UNICEF, and others, have estimated the effectiveness of various water, sanitation, and hygiene (WASH)-related interventions on early childhood diarrhea for children in low- and middle-income countries. The work relies heavily on randomized controlled trials led by Emory researchers over the past decade, in a shift from observational studies that form the traditional evidence base in environmental health. It provides the most rigorous assessment to date on the expected reduction in diarrheal disease burden through investing in improvements in WASH infrastructure and programming.