Although substance abuse often accompanies delinquency and other forms of antisocial behavior, there is less scholarly agreement about the timing of substance use vis-à-vis an individual’s antisocial trajectory. Similarly, although there is extraordinary evidence that onset is inversely related to the severity of the criminal career, there is surprisingly little research on the offense type of onset or the type of antisocial behavior that was displayed when an individual initiated his or her offending career. Drawing on data from a sample of serious adult criminal offenders (N = 500), the current study examined 12 forms of juvenile delinquency (murder, rape, robbery, aggravated assault, burglary, larceny, auto theft, arson, weapons, sexual offense, drug sales, and drug use) in addition to age at arrest onset, age, sex, race to explore their association with chronicity (total arrests), extreme chronicity (1 SD above the mean which was equivalent to 90 career arrests), and lambda (offending per year). The only onset offense type that was significantly associated with all criminal career outcomes was juvenile drug use. Additional research on the offense type of delinquent onset is needed to understand launching points of serious antisocial careers.