Clinical impressions and data from a limited number of studies suggest that membership in certain groups such as Alcoholics Anonymous may promote well-being and abstinence from alcohol and drugs. The present study examines measures of religiosity and drug/alcohol consumption in an inpatient psychiatric population in order to test the possible association between these variables. One hundred sixty-eight adult admissions to a private psychiatric hospital were asked to complete the Religious Involvement Questionnaire (RIQ), a self-report instrument containing validated measures of intrinsic and extrinsic religiosity. Responses of general adult psychiatric patients (N = 103) were compared with those of patients admitted to a chemical dependence unit (N = 65). Correlations between alcohol/drug use and RIQ responses were measured for the entire sample. Patients admitted for chemical dependence were significantly less likely than general adult psychiatry patients to avoid certain food/music/drink because of their religion, and were less likely to help with the running of their church. Measures of alcohol, hallucinogen, and prescription drug consumption had significant negative correlations with religiosity scores. Chemically dependent patients differ from psychiatric patients with other diagnoses on measures of religiosity. Religious belief and involvement may be clinically relevant variables in the treatment outcome of chemically dependent patients.