Background: Alcohol abuse and dependence can be disabling disorders, but accurate information is lacking on the prevalence of current DSM-IV alcohol abuse and dependence and how this has changed over the past decade. The purpose of this study was to present nationally representative data on the prevalence of 12-month DSM-IV alcohol abuse and dependence in 2001–2002 and, for the first time, to examine trends in alcohol abuse and dependence between 1991–1992 and 2001–2002. Methods: Prevalences and trends of alcohol abuse and dependence in the United States were derived from face-to-face interviews in the National Institute on Alcohol Abuse and Alcoholism’s (NIAAA) 2001–2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC: n=43,093) and NIAAA’s 1991–1992 National Longitudinal Alcohol Epidemiologic Survey (NLAES: n=42,862). Results: Prevalences of DSM-IV alcohol abuse and dependence in 2001–2002 were 4.65 and 3.81%. Abuse and dependence were more common among males and among younger respondents. The prevalence of abuse was greater among Whites than among Blacks, Asians, and Hispanics. The prevalence of dependence was higher in Whites, Native Americans, and Hispanics than Asians. Between 1991–1992 and 2001–2002, abuse increased while dependence declined. Increases in alcohol abuse were observed among males, females, and young Black and Hispanic minorities, while the rates of dependence rose among males, young Black females and Asian males. Conclusions: This study underscores the need to continue monitoring prevalence and trends and to design culturally sensitive prevention and intervention programs.