This study examined how adverse childhood experiences (ACE) may explain disparities in poor mental health between lesbian, gay, and bisexual (LGB), and heterosexual adults. Data are from three US states' 2010 behavioral risk factor surveillance system surveys (n = 20,060) that included sexual orientation, ACE inventory, and mental distress. LGB status was significantly associated with mental distress (OR = 1.85 [1.14-3.02]). Once incorporating ACE scores into the multiple regression analysis, LGB status was no longer associated with mental distress (OR = 1.28 [0.76-2.16]). The results corroborate previous research that LGB individuals report greater prevalence of childhood adversity than their heterosexual peers, which may explain LGB adulthood health disparities.