Abstract Background. Healthy Startis a 3-year demonstration and education research project designed to evaluate the effectiveness of a multidimensional cardiovascular (CV) risk reduction intervention in preschool centers over a 3-year period of time. Methods.Two primary interventions are employed. The first is the preschool food service intervention program designed to reduce the total fat in preschool meals and snacks to less than 30% of calories and reduce the saturated fat to less than 10% of calories. The second major intervention is a comprehensive preschool health education curriculum, focused heavily on nutrition. Results.Effectiveness of the intervention will be determined through evaluation of changes in dietary intake of preschool children at school meals and snacks, especially with respect to intake of total and saturated fat. Evaluation of the education component will include assessment of program implementation by teachers, assessment of changes in nutrition knowledge by preschool children, and assessment of changes in home meals that children consume (total and saturated fat content). Blood cholesterol will be evaluated semiannually to evaluate changes that may be due to modification of dietary intake. Growth and body fatness will also be assessed. Conclusions.While substantial efforts have targeted CV risk reduction and health education for elementary school children, similar efforts aimed at preschool children have been lacking. The rationale for beginning CV risk reduction programs for preschool children is based upon the premise that risk factors for heart disease are prevalent by 3 years of age and tend to track over time, most commonly hypercholesterolemia and obesity, both related to nutrition. Since the behavioral antecedents for nutritional risk factors begin to be established very early in life, it is important to develop and evaluate new educational initiatives such as Healthy Start, aimed at the primary prevention of cardiovascular risk factors in preschool children. The purpose of this publication is to describe the rationale and methods for the Healthy Startproject.