This study, which positions adult family members as health advocates and active promoters of their children's health, explicates the health beliefs and health actions of adult caregivers in limiting children's fast food consumption to prevent childhood obesity. Based on a survey of 124 parents, grandparents, and older siblings in Singapore, this study, which is grounded in the Health Belief Model, found that the strongest predictor of adult family members' behaviors to limit children's consumption of fast food is cues to action, or external stimuli. Adult family members who have greater exposure to news stories, media campaigns, and personal interactions and discussions about fast food are most likely to limit their children's consumption of fast food. Adult family members who perceive their children's higher susceptibility to childhood obesity also are more likely to limit their children's fast food consumption. Similarly, family members who view more seriously childhood obesity as a life-threatening illness are more likely to limit their children's fast food consumption. Finally, adult family members who consider fast food advertising to be less ethical are more likely to limit their children's consumption of fast food. Theoretical and practical implications are discussed.