As part of a family cardiovascular health promotion project, 111 Mexican-American and 95 Anglo-American families with fifth- or sixth-grade children were assigned to either a primary prevention program involving 18 sessions or to a control condition. This article evaluates predictors of attendance at the year long sequence of sessions in the intervention group. In addition it considers the relationship between attendance and program outcomes. Low baseline scores on physical activity and cardiovascular fitness measures were associated with higher attendance for both children and adults. High initial health knowledge and self-motivation were also associated with attendance. Multiple regression analysis showed that adult attendance was significantly predicted by a model including completion of a three-day food record, low exercise, higher socioeconomic status, family adaptability, and self-motivation. Attendance was correlated with greater knowledge gains and larger reductions in blood pressure. The results indicate that motivated families who are in greater need of conditioning attended more sessions in a health promotion program.