Late bedtimes in adolescence may be a serious risk factor for later poor health and functional outcomes. The current study sought to extend existing cross sectional data by examining whether late bedtimes in adolescence predicts poor outcomes in young adulthood. Data from wave 2 (1996) and wave 3 (2001–2002) of the nationally representative sample of US youth (National Longitudinal Study of Adolescent Health) was used to examine the longitudinal relationship between late bedtime, and several risk behaviors and negative health outcomes following 3,843 adolescents into young adulthood. At wave 2 the mean age was 16 with 52.1 % female. At wave 3 the mean age was 21.8. In cross sectional analyses, late bedtime was associated with 1.5 to over 3 times greater odds of involvement in risk behaviors and negative health outcomes, including emotional distress, suicidality, criminal and violent activity, and use of cigarettes, alcohol and illicit drugs. In longitudinal analyses, late bedtime assessed at wave 2 predicted a number of serious health outcomes at wave 3, with late bedtime in adolescence associated with around 1.5 greater odds of involvement in health jeopardizing behaviors such as criminal activity, alcohol abuse, cigarette use, illicit drug use and emotional distress in young adulthood. There was also a dose effect, such that the later the bedtime in adolescence, the greater the risk of involvement in risk behaviors in young adulthood. This research suggests that late bedtime in adolescence predicts multiple serious risk behaviors and health outcomes in young adulthood.