Although young adulthood is often characterized by rapid intellectual and social development, college-aged individuals are also commonly exposed to circumstances that place them at risk for psychiatric disorders. To assess the 12-month prevalence of psychiatric disorders, sociodemographic correlates, and rates of treatment among individuals attending college and their non-college-attending peers in the United States. Face-to-face interviews were conducted in the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (N = 43,093). Analyses were done for the subsample of college-aged individuals, defined as those aged 19 to 25 years who were both attending (n = 2188) and not attending (n = 2904) college in the previous year. Sociodemographic correlates and prevalence of 12-month DSM-IV psychiatric disorders, substance use, and treatment seeking among college-attending individuals and their non-college-attending peers. Almost half of college-aged individuals had a psychiatric disorder in the past year. The overall rate of psychiatric disorders was not different between college-attending individuals and their non-college-attending peers. The unadjusted risk of alcohol use disorders was significantly greater for college students than for their non-college-attending peers (odds ratio = 1.25; 95% confidence interval, 1.04-1.50), although not after adjusting for background sociodemographic characteristics (adjusted odds ratio = 1.19; 95% confidence interval, 0.98-1.44). College students were significantly less likely (unadjusted and adjusted) to have a diagnosis of drug use disorder or nicotine dependence or to have used tobacco than their non-college-attending peers. Bipolar disorder was less common in individuals attending college. College students were significantly less likely to receive past-year treatment for alcohol or drug use disorders than their non-college-attending peers. Psychiatric disorders, particularly alcohol use disorders, are common in the college-aged population. Although treatment rates varied across disorders, overall fewer than 25% of individuals with a mental disorder sought treatment in the year prior to the survey. These findings underscore the importance of treatment and prevention interventions among college-aged individuals.