In the United States, there have been five large, third-generation, epidemiological community studies conducted that help shed light on the epidemiology of singly diagnosed patients with SUDs (see Table 38–2) and the dually diagnosed: 1) the Epidemiologic Catchment Area (ECA) study (Regier et al. 1990), sponsored by the National Institute of Mental Health (NIMH) and conducted in five U.S. communities in households and institutional settings from 1980 to 1984; 2) the National Comorbidity Survey (NCS; Kessler et al. 1996), sponsored by NIMH and conducted with household and college residents throughout the country from 1990 to 1992; 3) the National Longitudinal Alcohol Epidemiologic Survey (NLAES; Grant and Pickering 1996), sponsored by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and conducted nationally with household residents from 1991 to 1992; 4) the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; Stinson et al. 2005), sponsored by NIAAA and conducted from 2001 to 2002 nationally in the civilian noninstitutionalized population; and 5) the National Comorbidity Survey Replication (NCS-R; Kessler and Merinkangas 2004), sponsored by NIMH and the National Institute on Drug Abuse and conducted nationally with household residents. Based on these studies (see Table 38–2), the current prevalence of alcohol use disorders (AUDs) and drug use disorders (DUDs) ranges from 4.4% to 9.7% and from 1.5% to 3.6% of the population, respectively, and the lifetime prevalence of AUDs and DUDs ranges from 13.5% to 30.3% and from 6.1% to 13.8%, respectively.