The Child and Adolescent Trial for Cardiovascular Health (CATCH) is a multicenter trial designed to test the effectiveness of school and family-based cardiovascular health promotion for preadolescents. CATCH interventions target multiple cardiovascular health behaviors such as dietary intake of fat and sodium, physical activity, and tobacco use. Evaluation includes physiological, psychosocial, behavioral, and process measures. An important aspect of the process evaluation is the assessment of environmental factors and "secular events" in both intervention and control schools that may affect outcomes independently of the CATCH interventions. With such information, CATCH investigators are able to isolate the impact of the CATCH intervention from competing (non-CATCH) factors as well as "track" proximal (i.e., immediate and short term) changes related to the intervention that may in turn lead to "distal" (long-term) behavior change. The School Health Questionnaire, the major process evaluation tool for monitoring secular and environmental changes in the schools, is described in detail, and data describing tobacco-related environmental factors and secular events are presented.