Purpose: The purpose of this study was to explore the association between sexual orientation and teen pregnancy (before age 20 years) in a U.S. nationally representative cohort of young adult females aged 24-32 years. Methods: A total of 5,972 participants in Waves I and IV of the National Longitudinal Study of Adolescent to Adult Health were included. Self-reported sexual orientation identity was categorized as heterosexual, and three sexual minority (SM) groups: mostly heterosexual, bisexual, and lesbian (combining "mostly homosexual" and "100% homosexual"). Stepwise multivariate regression models were fit to compare odds of teen pregnancy and relative risk ratios of timing of teen pregnancy, between heterosexual and SM groups, adjusting for sociodemographic characteristics, sexual victimization history, and sexual risk behaviors. Results: After adjusting for sociodemographics and sexual victimization, bisexual women had significantly higher odds than heterosexual peers of teen pregnancy (odds ratio [OR] = 1.70; 95% confidence interval [CI] = 1.05-2.75); this association was marginally significant after adjusting for sexual risk behaviors. Bisexuals were also more likely to have an early (before age 18 years) teen pregnancy (OR = 2.04; 95% CI = 1.17-3.56). In contrast, lesbian women were significantly less likely to have a teen pregnancy than heterosexual (OR = .47; 95% CI = .23-.97), mostly heterosexual (OR = .46; 95% CI = .21-.99), and bisexual (OR = .29; 95% CI = .12-.71) women in final models. Conclusions: Expanding on extant literature, we found opposing risk patterns for teen pregnancy between bisexual and lesbian women, likely due to distinct patterns of sexual risk taking. Findings suggest that SM-inclusive teen pregnancy prevention efforts tailored to meet the unique needs of SM young women, particularly bisexuals, are needed. (C) 2016 Society for Adolescent Health and Medicine. All rights reserved.