Research is lacking on how to make effective programs available on a large scale and how to maintain levels of implementation. CATCH: A Study of Institutionalization (CATCH-ON) was designed to help us understand the conditions under which such programs are institutionalized after the trial has ended. The Child and Adolescent Trial for Cardiovascular Health (CATCH) was the largest field trial of school-based health promotion in the United States conducted in 96 schools in four geographic areas of the United States: California, Louisiana, Minnesota. and Texas. The intervention was multicomponent, targeting school policy and practices in nutrition, physical activity, health education, and smoking. This report provides background on the CATCH study design, the conceptual framework for research on institutionalization of the CATCH program, and an overview of the seven original reports that present results from the CATCH-ON study in this theme issue.