We explored factors predicting repeated or hazardous alcohol use among autistic and non-autistic U.S. youth ages 16 to 20 years. Autistic (n = 94) and non-autistic (n = 92) youth completed an online survey. By design, half of each group reported past-year alcohol use. We compared drinking patterns for autistic and non-autistic youth, and within each group between abstinent or infrequent drinkers (0-1 drinking episodes in past year) versus those who drank 2 + times in past year. Autistic (vs. non-autistic) youth who drank did so less frequently and consumed fewer drinks per occasion. However, 15% of autistic youth who drank in the past year reported heavy episodic drinking and 9.3% screened positive for AUDIT-C hazardous drinking. For autistic youth only, a diagnosis of depression, bullying or exclusion histories were positively associated with drinking 2 + times in the past year. Autistic youth who put more effort into masking autistic traits were less likely to report drinking 2 + times in the past year. As compared to non-autistic youth, autistic participants were less likely to drink for social reasons, to conform, or to enhance experiences, but drank to cope at similar rates. Repeated and hazardous underage alcohol occur among autistic youth. Targeted prevention programs designed to address the specific drinking profiles of autistic youth are needed.