Studies have focused on serious, violent, or habitual offenders and have varied in terms of offenses, ages of juveniles, and criteria (arrest, charge, arraignment, conviction). Development of a standardized definition would permit more accurate identification of the target population and would aid in policymaking and programming. Such a definition should include a minimum age, specific offenses to be included, inclusion criteria (e.g., arrest, conviction), total number of offenses, and drug or alcohol involvement. By classifying juveniles as serious/nonserious habitual/nonhabitual, and drug involved/noninvolved, eight classes of juvenile offenders can be delineated. These classes cover the range of delinquent types and could provide the basis for the development of standard definitions for each class of juvenile offenders. 1 figure, 29 footnotes, and references.