Sexual minority youth report higher rates of depression and suicidality than do heterosexual youth. Little is known, however, about whether these disparities continue as youth transition into young adulthood. The primary goals of this study were to describe and compare trajectories of adolescent depressive symptoms and suicidality among sexual minority and heterosexual youth, examine differences in depressive symptoms and suicidality trajectories across sexual orientation subgroups, and determine whether there are gender differences in these longitudinal disparities. Four waves of data from the National Longitudinal Study of Adolescent Health were analyzed using latent curve modeling (N = 12,379; 53% female). Results showed that the rates of depressive symptoms and suicidality in early adolescence were higher among sexual minority youth than among heterosexual youth, and that these disparities persisted over time as participants transitioned into young adulthood. Consistent with previous cross-sectional studies, the observed longitudinal disparities were largest for females and for bisexually-identified youth. Sexual minority youth may benefit from childhood and early adolescent prevention and intervention programs.