The HEALTHY Study was a 3-year school-based intervention designed to change the behaviors of middle school students to reduce their risk for developing type 2 diabetes mellitus. This report examines the relation between exposure to communications campaign materials and behavior change among students in the HEALTHY intervention schools. Using data from campaign tracking logs and student interviews, the authors examined communications campaign implementation and exposure to the communications campaign as well as health behavior change. Campaign tracking documents revealed variability across schools in the quantity of communications materials disseminated. Student interviews confirmed that there was variability in the proportion of students who reported receiving information from the communication campaign elements. Correlations and regression analysis controlling for semester examined the association between campaign exposure and behavior change across schools. There was a significant association between the proportion of students exposed to the campaign and the proportion of students who made changes in health behavior commensurate with study goals. The results suggest that, in the context of a multifaceted school-based health promotion intervention, schools that achieve a higher rate of exposure to communication campaign materials among the students may stimulate greater health behavior change.