The 892 participants were ages 12 and 15 at the time of their initial interviews in 1979-81 and were 15 and 18 when interviewed 3 years later. They were grouped according to their levels of marijuana use and delinquency over time. Results supported the independent cause hypothesis. The specific mode of friends' deviance clearly differentiated between deviants who became more involved in marijuana use and those who became more involved in delinquency. However, while several personality variables reliably distinguished deviants from nondeviants, they did not differentiate between marijuana users and juvenile delinquents. Tables and 63 references (Author abstract modified)