BACKGROUND Few nutrition interventions in kindergarten classes have been evaluated, and none has been tested for program effectiveness, implementation, and dissemination. Building a Healthy Me (BHM) is a nutrition intervention for kindergarteners that is classroom‐based and includes a family component. This study evaluated the public health impact of BHM in California kindergarten classrooms using the RE‐AIM (reach, efficacy, adoption, implementation, and maintenance) framework. METHODS A quasi‐experimental design assessed pre‐to‐post changes in nutrition knowledge, dietary consumption, and parent behaviors of 25 intervention classrooms (414 students, 264 parents); and postintervention differences in nutrition knowledge between the intervention classrooms and 4 control classrooms measured at postintervention only (103 students). RESULTS Intervention students improved in knowledge of food groups and healthy breakfast/snack options, and scored higher than control students in food group knowledge at postintervention (ps < .05). Parents of intervention group children increased their use of food labels, and intervention group children increased intake of several healthy foods and decreased intake of candy and fried potatoes (ps < .05). The BHM program reached 41% of kindergarteners attending public schools in California, and teachers implemented most lesson material. CONCLUSIONS The BHM program was effective, implemented with fidelity, and broadly disseminated, highlighting its potential public health impact for kindergarteners.