The data were collected in 1986 and 1987 and covered a 24-month period following completion of the last year of high school. Information was collected in Edmonton, Toronto, and Sudbury. A total of 1,030 youths, including 49 percent males and 51 percent females, participated. According to the model, young adults with less job stability and weaker occupational and educational commitment should be freer from informal social controls and therefore more at risk for an increased level of marijuana use. However, results revealed that none of the measures of informal social control processes was an important net predictor of change in marijuana use. Instead, previous marijuana use in high school was of overwhelming importance in predicting use 2 years later. Data also indicated that having delinquent friends led to increased marijuana use. Tables and 59 references