Objective: This study examined the location and time of adolescent use of cigarettes, alcohol, and marijuana. Age, gender, and racial differences in location and time of use were studied for each substance. Method: Using cross-sectional data collected through the school-wide Pride Survey, 20,055 students between the ages of 10 and 19 years (53.6% female, 55.1% Black, 44.9% White) in one metropolitan area reported on their frequency of cigarette, alcohol, and marijuana use, as well as the location and time of use of each substance. Chi-square tests compared the rates, locations, and times for each substance across boys and girls; Black and White students; and early, middle, and late adolescents. Results: Older adolescents reported higher rates of substance use at friends' homes, at school, and in cars and lower rates of alcohol use at home compared with younger youth. Males were more likely to report alcohol and marijuana use at school and on weeknights and alcohol use in cars, whereas females were more likely to report alcohol and marijuana use on the weekends. No gender differences emerged for times and locations of cigarette use. Compared with Black youth, White adolescents were more likely to use all substances at friends' homes and on weekends; to smoke cigarettes at school, in the car, and on week-nights; and to use alcohol at home. Black adolescents were more likely to report using alcohol at home, at school, in cars, during and after school, and on weeknights and were more likely to report using marijuana at school. Conclusions: The location and time of adolescent substance use vary substantially by age, gender, and race. These differences may help tailor substance use prevention and intervention programs to specific subgroups of youth to improve program effectiveness.