Previous research has established a relationship between cigarette smoking and substance use among community and school samples, yet little is known about the association between smoking and substance use among adolescents in psychiatric treatment. The current study explored the daily smoking and substance use patterns among a sample of 191 adolescents who were hospitalized in a private psychiatric hospital. Participants completed several measures of smoking and drinking frequency and intensity, including the Customary Drinking and Drug Use Record and the Fagerstrom Tolerance Questionnaire. Results of statistical analyses revealed that the participants smoked an average of 91 percent of the days during the 3 months leading to their hospitalization and smoked an average of 13.9 cigarettes per smoking day. Recent marijuana use was associated with frequent cigarette use while recent binge drinking was associated with intense cigarette use. Participants smoked significantly more cigarettes on days they reported consuming alcohol or other drugs. The findings indicate that smoking cessation programs are needed for adolescent psychiatric populations and should also target other substance use problems. Tables, references