In attempting to address these concerns, the current research relied on data from the 1992 National Longitudinal Alcohol Epidemiologic Survey (NLAES). The NLAES consisted of personal interviews with 42,862 adults aged 18 years and older who were randomly selected from a nationally representative sample of households. Diagnoses of DSM-IV alcohol and drug use disorders were derived from the Alcohol Use Disorders and Associated Disabilities Interview Schedule, a structured psychiatric interview designed to be administered by trained interviewers who were not clinicians. Data analysis focused on episode or period comorbidity, the co-occurrence of two or more psychiatric disorders during the same time period. Results demonstrated a pervasive co-occurrence of alcohol and drug use disorders in the general population. In addition, the comorbidity of alcohol and drug dependence was significantly greater than the comorbidity of alcohol and drug abuse. Further research is recommended to examine the heterogeneity of people with alcohol and drug use disorders. 16 references and 3 tables