This study sought to characterize adolescent psychiatric inpatient populations from two sites and to determine correlates of substance use disorders (SUD). Screening procedures for SUD differ substantially between these sites. A retrospective review of adolescent inpatients (n=636) revealed that the populations were similar in gender, race and age. Rates of SUD at the site with a formalized SUD screening regimen were higher (39%) than those at the other site (16.5%). Similar correlates of SUD were observed across sites, including older age, legal involvement, sexual activity, childhood disruptive disorder, and tobacco use. These results suggest that SUD is a major issue in adolescent psychiatric patients. More rigorous screening for SUD and its correlates may facilitate earlier detection of substance use in this vulnerable population.