4. 72 consecutive hours of abstinence from alcohol, determined by self-reports and confirmed by a negative breathalyzer tests, and a Clinical Institute Withdrawal Scale for Alcohol (CIWA-AR) (Sullivan, 1989) score below eight. Subjects will be encouraged to achieve 72 consecutive hours of abstinence, however, subjects who have achieved between 48 and 72 consecutive hours of abstinence will be included with the approval of the principal investigator. We anticipate that these subjects will comprise less than 5% of total enrolled subjects. Subjects will be given 2 additional weeks beyond the screening week to attain the appropriate period of alcohol abstinence prior to randomization.