A prospective investigation was conducted to evaluate the accuracy of internalizing and externalizing traits measured at ages 10–12 for predicting a DSM-IV diagnosis of cannabis use disorder manifest by age 22. The sample consisted of 189 boys rated on the Child Behavior Checklist (CBCL) by their biological mothers. The results indicated that externalizing but not internalizing disturbance was a significant predictor of cannabis use disorder. Moreover, a construct capturing their common variance did not predict cannabis use disorder better than externalizing behavior alone.