This thesis explores the effectiveness of wellness policies in promoting healthy

behaviors by combining a theoretical model with empirical evidence from a U.S.

wellness initiative: the Comprehensive School Physical Activity Program (CSPAP),

which is designed to improve adolescent health and combat obesity. The model pre-

dicts that only individuals with intermediate preferences are likely to change their

behavior in response to policy interventions when the primary mechanism is in-

creased accessibility to wellness activities (e.g., physical activity). It also suggests

that policies may have a greater impact on health outcomes when accessibility is

combined with educational interventions. Empirically, the results reveal a statis-

tically significant two-year-lagged reduction in obesity rates, particularly in states

with higher adoption intensity. This finding is consistent with the model’s predic-

tion: pairing accessibility with education can amplify the policy’s effect on health

outcomes. The effect is estimated to have lowered national obesity among high

school students by up to 2.7 percentage points in 2022. These findings draw at-

tention to the importance of program intensity and sustained implementation in

shaping public health outcomes.