Sexual minority youth experience disproportionate rates of mental health symptomatology relative to their heterosexual peers. Less is known about why these disparities have persisted despite growing public awareness of sexual diversity. The developmental collision hypothesis states that increased cultural visibility of sexual diversity has accelerated the developmental timing of sexual minority identity formation processes such that they collide with early adolescence, a uniquely sensitive period for experiencing identity-based stigma and associated mental health vulnerability. To test this hypothesis, levels and relations between ages of sexual minority identity development milestones, frequency of LGBT-related victimization, and depressive symptoms were examined across three age-matched but cohort-distinct samples of sexual minority adolescents. Data come from three secondary datasets of sexual minority youth who were adolescents in the 1990s, 2000s, and 2010s, respectively: the Challenges and Coping Study, the Victimization and Mental Health among High Risk Youths Study, and the Risk and Protective Factors for Suicide among Sexual Minority Youth Study (n = 1312; Mage = 17.34, SD = 1.30; 52% female). Adolescents from more recent cohorts reported earlier mean ages of several milestones but similar frequencies of LGBT-related victimization relative to those from less recent cohorts. Path analysis models showed that earlier milestones were associated indirectly with more depressive symptoms through LGBT-related victimization. Notably, earlier ages of self-identification and disclosure of a sexual minority identity were also directly related to less depressive symptoms. Few generational differences in relations between constructs emerged. Findings garner initial support for the developmental collision hypothesis and suggest that LGBT-related victimization, rather than earlier milestones themselves, increases mental health vulnerability.
