Worldwide, over 2.5 billion people lack access to basic sanitation, a situation that contributes to 2 million annual diarrhea-related child deaths and substantial morbidity. Yet rigorous evaluations of sanitation behaviors and their health and welfare impacts are rare. This article uses a randomized sanitation promotion campaign in Orissa, India, to evaluate child health and household welfare outcomes. The sanitation campaign increased households’ ownership and use of latrines and improved children’s mid-upper-arm circumference, height, and weight z-scores. Switching from open defecation to latrine use also saved time and increased satisfaction in sanitation conditions. We use our results to illustrate the cost-benefit calculus underlying this seemingly unglamorous and mundane household choice with potentially large environmental externalities.