The effects of cardiovascular risk reduction are typically assessed by self-reported behavior change and physiological outcomes. There is a need to enhance evaluation protocols by including direct observation measures of targeted health behaviors. To improve the evaluation of a family-based diet and physical activity change program, families were observed during a planned visit to the San Diego Zoo. This standardized environment afforded many options for dietary intake and physical activity. Thirty families who had participated in a 1-year intervention program and 30 control families were observed. Caucasian and Mexican-American families were equally represented. Observations in this standard environment discriminated between intervention and control families, and the findings indicated that intervention effects generalized to this novel setting. Intervention families consumed fewer calories, ate less sodium, and walked further than did control families. Ethnic differences were noted.