This study examined relationships between timing of gay-related developmental milestones, early abuse, and emergence of poor health outcomes in adulthood among 1,383 gay/bisexual men in the Urban Men's Health Study. Latent Profile Analysis grouped participants as developing early, middle or late based on the achievement of four phenomena including age of first awareness of same-sex sexual attractions and disclosure of sexual orientation. Participants who developed early were more likely, compared to others, to experience forced sex and gay-related harassment before adulthood. They were more likely to be HIV seropositive and experience gay-related victimization, partner abuse and depression during adulthood. Early forced-sex, gay-related harassment and physical abuse were associated with several negative health outcomes in adulthood including HIV infection, partner abuse, and depression. This analysis suggests that the experience of homophobic attacks against young gay/bisexual male youth helps to explain heightened rates of serious health problems among adult gay men.