This study investigated the age of onset of substance use among 536 students with mild academic disabilities and 906 students without academic disabilities, and the extent to which emotional, conduct, and hyperactivity problems explain the differences between these two groups. Using discrete-time survival analysis, the results of this study showed that students with a mild academic disability were not at higher risk for the onset of daily smoking, and were at a significantly lower risk for the onset of weekly alcohol use and cannabis use. Though students with a mild academic disability displayed higher scores on conduct, emotional, and hyperactivity problems compared with their counterparts without an academic disability, this was not reflected in an increased risk for early onset substance use.