The purpose of this study is to evaluate the effects of the study medication, memantine (placebo, 20 mg or 40 mg/day) on alcohol drinking behavior in a laboratory setting in which participants are given an initial drink of alcohol followed by the choice to drink up to 12 more drinks over a three-hour period. We hypothesize that memantine will reduce craving and number of drinks consumed prior to and after exposure to the initial drink of alcohol and during the three hour drinking period. We will also evaluate the influence of family history of alcoholism on the efficacy of memantine in reducing alcohol drinking behavior.