To better understand the institutionalization process in Child and Adolescent Trial for Cardiovascular Health (CATCH) intervention and control schools, 199 key informant interviews were conducted with school food service staff, physical education teachers, classroom teachers, and administrators at the four CATCH-ON field centers. School personnel were asked to talk about the degree of CATCH program implementation, who at the school or school district was instrumental in promoting CATCH, and the conditions that facilitated or impeded the institutionalization of CATCH activities and philosophies. The CATCH Physical Education (PE) component appeared to have the highest level of institutionalization, and the CATCH classroom curriculum and family components appeared to have the lowest levels of institutionalization. The primary barriers expressed included the low priority for health promotion activities and time constraints of schools: lack of mechanisms for training of school staff; and lack of sufficient funds for materials, equipment, and lower fat vendor products.