The Children's Activity Trial of Cardiovascular Health (CATCH) is a phased clinical trial of school-based interventions targeting maintenance of non-smoking, decreasing high sodium and high saturated fat food intake, and increasing regular physical activity. The clinical trial will test the effectiveness of changes in the school environment and parent involvement designed to augment the impact of a school-based cardiovascular curriculum compared to the standard health curriculum given to 5th and 6th grade students. The San Diego CATCH investigators are a multidisciplinary research group with expertise in the target areas of smoking, diet, exercise, family, school, and environmental manipulations. The scope of experience includes curriculum development, implementation of interventions with schools, families, formative and summative evaluation of these demonstrations, and extensive methodologic research on reliability and validity of self-reported physical activity and dietary behaviors. During Phase One, the San Diego CATCH investigators will collaborate with the other Study Centers to design the study protocol, determine the cardiovascular curriculum parent program and school environmental interventions to be used. We propose a Social Learning Theory (SLT) framework to be utilized to select and test the best approaches. We will collaborate with the other Study Centers to determine the instruments and methods for measuring knowledge, behavioral intentions, and behavior as well as process and compliance/quality assurance measures. Reliability and validity studies will need to be accomplished. The San Diego CATCH investigators already have considerable experience in reliability and validity measures of diet and physical activity in children and adults which can be helpful to other CATCH investigators. We also have extensive intervention and measurement experience with Spanish speaking subjects. Other Phase One goals will include pilot of the intervention, determination of participation rates and feasibility and cost estimates for future phases of CATCH. Excellent relationships and cooperation with several San Diego county school districts will ensure over 21,571 5th and 6th grade students and 135 elementary schools available to the investigators. All these factors contribute to a high likelihood of meeting project objectives.