Does sexual debut (i.e., experiencing sexual intercourse for the first time) increase the risks of participating in later delinquent behavior? Does this risk increase if adolescents experience early sexual debut relative to the timing experienced by one's peers? Although many factors have been linked to sexual debut, little research has examined whether sexual initiation is linked to later behavioral outcomes. Using data on adolescents participating in three waves of the National Longitudinal Study of Adolescent Health (N = 7,297), we examine the interconnections between sexual debut and later delinquency. In addition, we pay particular attention to the role of timing of sexual debut. We find that experiencing sexual debut is associated with delinquency one year later. In addition, those adolescents who experience early sexual debut relative to their peers are at higher risk of experiencing delinquency compared to those who debut on-time; adolescents who experience late sexual debut are the least likely to participate in delinquency. Moreover, the protective effect of late sexual debut appears to persist for several years. Findings are interpreted by drawing on developmental theory and life course research.