Afterschool programs in California have the potential to play a major role in obesity prevention given that they serve close to a million low-income children. A five-year initiative called the Healthy Eating Active Communities (HEAC) was funded in 2005 by the California Endowment to demonstrate that disparities related to childhood obesity and diabetes could be reduced in communities that offered families accessible and affordable opportunities for healthy eating and physical activity. The afterschool program setting constituted one of five key settings targeted in the initiative. This chapter describes the HEAC afterschool program initiative, reviews findings from the HEAC afterschool program nutrition and physical activity evaluation, and shares strategies that were used to implement the five-year training and technical assistance intervention.