The problem of adolescent substance use has been examined extensively. Beyond simple prevalence estimates, however, little research has been conducted on substance use in the school context. The present investigation was an in-depth study of students' attitudes and behaviors regarding alcohol and marijuana use during the school day. Based on a representative sample of 1123 high school students, this study assessed the frequency of alcohol and marijuana use at school among demographic subgroups, the accessibility of drugs in school, and students' perceived consequences of being caught using drugs in school. The results showed that male and Hispanic students had higher levels of drug use at school than female and white students, respectively; that school drug use increased with age, and that alcohol and marijuana were easily obtained and used on school grounds. A large percentage of students were not aware of the specific actions taken in their schools to punish drug use. The need for additional research on school-related drug use is emphasized.