Background: Enforcement of no-tobacco policies is critical to providing a safe, healthy environment for students. Purpose: The purposes of the study were to: (1) describe and compare student and principal perceptions of enforcement of school tobacco policy in a school district with a tobacco-free policy, and (2) explore perceived barriers to enforcement and factors related to enforcement beliefs and perception of smoking. Methods: Students (N = 774) in five high schools in a southeastern city completed a survey. Administrators from those schools were interviewed. Results: Student and principal perceptions varied dramatically concerning tobacco policy enforcement. Only 8% of students said students followed the rules about smoking all/most of the time. Many students reported problems with secondhand smoke. The percentage of smokers was overestimated by nearly three-quarters of students (73%). Predictors of beliefs about number of tobacco rules were: smoking status, number of places students were seen smoking and number of problems reported with smoking. Barriers identified by principals included lack of supervisory help and that tobacco is physically addicting. Discussion: Student perception of how well tobacco policies are enforced should not be ignored by administrators because it is related to smoking behavior. Teachers, students, staff, administrators and parents must be enlisted to help enforce tobacco policy. Translation to Health Education Practice: To change the culture in schools, teachers, students, staff, administrators and parents must be educated about the tobacco policy, and tobacco rules must be consistently enforced. (Contains 5 tables.)