Engaging in a romantic relationship is a key developmental task of adolescence and adolescents differ greatly in both the age at which they start dating and in how romantically active they are. These differences in romantic relationship experiences could be relevant for adolescents’ short- and long-term psychosocial adjustment. The present study describes the diversity of relationship experiences during adolescence and examines their connection to psychosocial adjustment in adolescence and young adulthood. N  = 2457 adolescents (49.3% female) from a German representative longitudinal study provided information on their relationship experiences between the ages 10 and 20, as well as on their psychosocial adjustment. Data were collected via annual assessments starting in 2008 at age M  = 16.50 years ( SD  = 0.88) through young adulthood ( M  = 25.46, SD  = 0.87). Latent profile analysis identified three romantic involvement groups: late starters, moderate daters, and frequent changers, which were further compared to adolescents without any romantic experiences (continuous singles). Growth curve analyses indicated that continuous singles reported lower life satisfaction and higher loneliness than the moderate daters in adolescence and young adulthood. The continuous singles were also less satisfied with their life in young adulthood and felt more lonely in both adolescence and young adulthood compared to the late starters. The findings of the study suggest great variability in adolescents’ romantic relationship experiences and point toward the developmental significance of these experiences for short- and long-term well-being.