Objective: Few population-based studies have explored differences in alcohol consumption by sexual orientation. This study examined the prevalence of abstinence, drinking, heavier drinking, alcohol-related problems, alcohol dependence and help-seeking among homosexual and bisexual women and men compared with heterosexuals. Method: Data are from the 2000 National Alcohol Survey, a national population-based survey of adults (N = 7,612), a Random Digit Dialing telephone survey of all 50 states of the United States and Washington, DC. Four categories of sexual orientation were created using questions on both sexual orientation self-identification and behavior: homosexual identified, bisexual identified, heterosexual identified with same sex partners and exclusively heterosexual. Five alcohol measures (past year) were used in the analyses: (1) mean number of drinks, (2) days consuming five or more drinks on a single occasion, (3) drunkenness, (4) negative social consequences (2 or more) and (5) Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, alcohol dependence. A lifetime measure of help-seeking for an alcohol problem was also analyzed. Results: Few significant differences were found among men by sexual orientation. By contrast, both lesbians and bisexual women had lower abstention rates and significantly greater odds of reporting alcohol-related social consequences, alcohol dependence and past help-seeking for an alcohol problem. Conclusions: These findings suggest that alcohol dependence and alcohol-related consequences differ by sexual orientation, particularly among women. These findings also emphasize the need for the inclusion of sexual-orientation items in population-based surveys so that prevalence rates within these subgroups can be effectively monitored.