Many schools implement random student drug testing (RSDT) programs as a drug prevention strategy. This study analyzes self-report surveys of students in eight secondary schools with well-established RSDT programs, comparing students who understood they were subject to testing and students who understood they were not subject to testing. Students subject to testing reported significantly less marijuana and other illegal drug use than students in the same schools who were not subject to testing, and also had more positive attitudes toward testing. Alcohol use, which was not tested for in seven of the eight schools, did not differ between groups. This study provides evidence that awareness of eligibility for drug testing in schools with well-established RSDT programs is associated with lower rates of drug use. (Contains 4 figures, 4 tables and 3 notes.)