Evaluations of school-based substance abuse prevention programs with schools or school districts randomly assigned to either the treatment or control condition have demonstrated effective strategies over the past 30 years. Although control schools were never considered “pure” (i.e., no other interventions were being offered), school-based programming in the 1980s did not include evidence-based interventions. Since the late 1990s, funding agencies have required schools either to select programming from approved lists of prevention strategies or to demonstrate the efficacy of the strategies that would be used. This has increased the number of schools delivering evidence-based programs to their students. As a result, “treatment as usual” is more challenging to researchers. This paper describes exposure to prevention programming as reported by 204 school administrators from 83 districts and their 19,200 students who are participating in the Adolescent Substance Abuse Prevention Study, a national randomized evaluation trial of the program, Take Charge of Your Life. In order to determine the extent of student exposure to prevention programming in both the control and treatment schools, data were collected in each of the 5 years of the study from two sources: principals and prevention coordinators and from students. The data provided by the principals and prevention coordinators indicate that the vast majority of schools assigned to the control condition offered students drug prevention programming. This finding has implications for the evaluation of Take Charge of Your Life but also for other evaluation studies. The students were asked questions regarding participation in drug education posed on annual surveys. When their responses were compared to the reports from their school principals and prevention coordinators, it was found that the students underreported exposure to drug education. A follow-up qualitative study of a sample of students suggests the need for rewording of the questions for students in future studies. The implications of our findings for evaluation studies are discussed.