Data from 386 seventh grade students, 48% male and 65% white, were collected at two sites in North Carolina. The purpose of the study was to estimate the prevalence of alcohol and drug use among adolescents as part of a continuing study of preventive health behaviors. The data were collected anonymously from self-completed questionnaires and were analyzed by race and sex to determine knowledge of and attitudes toward alcohol and smoking, self-concept, and locus of control. Black boys had the highest prevalence of alcohol (16%) and tobacco (20%) use and at the same time had the lowest amount of knowledge about the dangers of the substances. White boys, while knowing more about the potential dangers, reported similar patterns of use. In general, girls used much less alcohol and tobacco and had higher levels of knowledge and more prudent attitudes. Boys, particularly blacks, were found to be at greater risk than girls of developing patterns of behavior that are associated with abuse of alcohol and heavy smoking. The findings suggest that health education to inform adolescents of the dangers of alcohol and smoking needs to be specific to cultural and sex groups. © 1986 Southern Medical Association.