The specific aims of the project are : (1) to place adolescents into groups either high or low risk for substance use on a set of risk variables; (2) to examine the trajectory of substance use of those in the high risk and low risk groups and to identify adolescents in the high risk group who either did not move into problem substance use by the end of the study period, and adolescents who significantly decreased their use. Adolescents in the low risk group who progressed into problem substance use during the study period will also be identified; and (3) to determine what characteristics distinguish between those adolescents who stayed on the expected trajectory for their risk category and those who moved off the expected trajectory.