Objective: To quantify the Head Start (HS) teacher mediating and moderating influence on the effect of a wellness policy intervention. Design: Intervention trial within a larger randomized community trial. Setting: HS preschools in Hawaii. Participants: Twenty-three HS classrooms located within 2 previously randomized communities. Intervention: Seven-month multi-component intervention with policy changes to food served and service style, initiatives for employee wellness, classroom activities for preschoolers promoting physical activity (PA) and healthy eating, and training and technical assistance. Main Outcome Measures: The Environment and Policy Assessment and Observation (EPAO) classroom scores and teacher questionnaires assessing on knowledge, beliefs, priorities, and misconceptions around child nutrition and changes in personal health behaviors and status were the main outcome measures. Analysis: Paired t tests and linear regression analysis tested the intervention effects on the classroom and mediating and moderating effects of the teacher variables on the classroom environment. Results: General linear model test showed greater intervention effect on the EPAO score where teachers reported higher than average improvements in their own health status and behaviors (estimate [SE] = -2.47 (0.78), P .05). Conclusions and Implications: Strategies to improve teacher health status and behaviors included in a multi-component policy intervention aimed at child obesity prevention may produce a greater effect on classroom environments. (author abstract)