This paper exploits state health education (HED) reforms as quasi-natural experiments to estimate the causal impact of HED received by children on their parents' physical activity. We use data from the Panel Study of Income Dynamics for the period 1999-2005 merged with data on state HED reforms from the National Association of State Boards of Education Health Policy Database and the 2000 and 2006 School Health Policies and Programs Study. To identify the spillover effects of HED requirements on parents' behavior, we use several methodologies (triple differences, changes in changes, and difference in differences) in which we allow for different types of treatments. We find a positive effect of HED reforms at the elementary school on the probability of parents doing light physical activity. Introducing major changes in HED increases the probability of fathers engaging in physical activity by between 6.3 and 13.7 percentage points, whereas on average, this probability for mothers does not seem to be affected. We analyze several heterogeneous impacts of the HED reforms to unveil the mechanisms behind these spillovers. We find evidence consistent with hypotheses such as gender specialization of parents in childcare activities or information sharing between children and parents.