This study examines mental health issues among women of different sexual orientations. An anonymous survey was administered at 33 health care sites across the United States; the sample (N = 1304) included lesbians (n = 524), bisexual (n = 143) and heterosexual women (n = 637). Not only did sexual orientation influence the probability of experiencing emotional stress, but also whether a bisexual woman or lesbian had disclosed her sexual orientation (was "out") impacted the likelihood of having or having had mental health problems. Bisexual women and lesbians experienced more emotional stress as teenagers than did heterosexual women. Bisexual women were more than twice as likely to have had an eating disorder compared to lesbians. If a bisexual woman reported being out she was twice as likely to have had an eating disorder compared to a heterosexual woman. Lesbians who were not out and bisexual women who were out were 2-2.5 times more likely to experience suicidal ideation in the past 12 months. Lesbians and bisexual women who were not out were more likely to have had a suicide attempt compared to heterosexual women. Lesbians used psychotherapy for depression more commonly than did heterosexual or bisexual women. This is one of the few studies that compares lesbians, bisexual and heterosexual women. The implications of these findings are discussed.