School surveys of alcohol, tobacco, and other drug (ATOD) use play an important role in prevention programs and policy development. Improving the quality of such data collection is critical. Most surveys are conducted with paper and pencil (PAP) instruments, but computer-assisted self interviews (CASI) are now being developed and there is some evidence that they elicit higher rates of positive responses to sensitive questions than traditional measures. The present study examines whether ATOD school surveys using CASI are feasible and improve the quality of data. Seventh, ninth, and eleventh grade students in two California communities were randomly assigned to PAP or to CAST (n = 2296). The findings indicate that while CAST did not increase reported rates of substance use over PAP, it significantly improved the speed of data processing and decreased the incidence of missing data. CASI was well accepted by students and school staff despite problems such as lack of computer resources. (C) 2000 Elsevier Science Ltd. All rights reserved.