Background: Heavy drinking college students are at risk for experiencing poor sleep and negative alcohol-and cannabis-related consequences. College students with attention-deficit/hyperactivity disorder (ADHD) are uniquely vulnerable to both poor sleep and negative consequences from alcohol and cannabis use. Thus, it is critical to consider relations between ADHD, sleep and alcohol-related negative consequences together in a single study. In the present study, we examined: (1) the associations among ADHD status, sleep and alcohol- and cannabis-related consequences; (2) the independent and interactive effects of sleep and ADHD on negative alcohol-related consequences. Finally, we explored the independent and interactive effects of sleep and ADHD on negative cannabis-related consequences. Method: College student drinkers with (n=51) and without (n=50) ADHD completed a 2-hour assessment that included measures of sleep quality, alcohol and cannabis use, and alcohol/cannabis-related negative consequences. Analyses utilized a series of hierarchical linear regression models to examine study aims. Results: College student drinkers with ADHD reported significantly worse sleep quality relative to non-ADHD student drinkers. Students with ADHD also experienced more negative alcohol-related consequences, relative to student drinkers without ADHD. When ADHD and sleep quality were included in the model together, ADHD—but not sleep quality—was independently associated with negative alcohol consequences, but not negative cannabis consequences. There were no moderating effects of ADHD on the associations among sleep and negative consequences resulting from either alcohol or cannabis use. Conclusion: This is the first study to examine sleep quality in college students with and without ADHD engaging in heavy drinking, as well as the first to examine the independent and interactive effects of sleep and ADHD on alcohol- and cannabis-related consequences. Results demonstrated that college drinkers with ADHD are particularly vulnerable to experiencing poor sleep and negative consequences from their alcohol and cannabis use, compared to their heavy drinking peers without ADHD. Future, larger scale studies should consider longitudinal effects as well as underlying mechanisms of risk.