The youths could be grouped into five categories, ranging from those who ceased their criminality to those who were arrested on felony charges twice or more per year for at least 2 consecutive years. Those most likely to become high-rate offenders were minority, living at home with their mother only, in a household supported only by welfare, and not doing well in school. First arrests at an early age and high rates of juvenile criminality were associated with greater likelihood of adult criminal careers. However, less than one in four members of this subgroup became high-rate offenders. Offenders did not specialize in one type of offense and did not escalate the seriousness of their criminal involvement, however. The criminal justice system did not receive information that would be useful in predicting criminality. The concepts underlying many arguments for selective incapacitation were not upheld. Future research should consider why the majority of juveniles do not continue to commit offenses after a certain age. Data tables and 18 references.