The Child and Adolescent Trial for Cardiovascular Health (CATCH) was the largest school-based field trial ever sponsored by the National Institutes of Health. The trial demonstrated positive changes in the school food service and physical education program, as well as in students' cardiovascular health behaviors. Because the CATCH intervention programs were implemented in 56 schools (in four states) that were typical of schools throughout the United States, their reception by schools and degree of implementation provide evidence about their feasibility for schools nationally. Extensive process evaluation data were collected from students, teachers, school food service personnel, and physical education specialists throughout the three school years of the CATCH intervention. Four of the CATCH programs--school food service, physical education, classroom curricula, and home programs--were assessed over the three school years. The process data provide information on participation, dose, fidelity, and compatibility of the CATCH programs in the intervention schools for these programs. High levels of participation, dose, fidelity, and compatibility were observed for the four programs during the 3 school years. CATCH emerges as a model of a feasible multilevel health promotion program to improve eating and exercise behaviors for elementary schools in the United States.