Heterogeneity of Juvenile Offending

Although this report focuses on the design and operation of the juvenile justice system, it is important to have a sense of some general characteristics of the offending behavior to which the system is expected to respond. Research on juvenile offending4 reflects substantial heterogeneity in the population of youth who can be considered delinquent. At one extreme, some youth commit only a few trivial offenses; at the other extreme, some youth commit many offenses, some of which are quite serious and violent.

The epidemiological literature shows that, regardless of how serious delinquents are defined,5 they constitute a very small proportion of the overall delinquent population. They do commit many offenses, but most of their offenses are relatively minor and there are extraordinarily few chronic violent offenders. The vast majority of youth who are arrested or referred to juvenile court are not serious delinquents, and half of them appear in the system only once.

Concern over serious delinquents emerged from the pioneering longitudinal studies of Wolfgang and colleagues (Wolfgang et al., 1972, 1987; Wolfgang, 1983) in their study of the 1945 birth cohort of males in Philadelphia. Using official arrest data to measure delinquency, they identified a group they called chronic offenders, youth who had been arrested five or more times. Although constituting only 6 percent of the total cohort and 18 percent of the delinquents (those who had been arrested at least once), chronic offenders were responsible for 52 percent of all the offenses committed. They also committed serious and violent offenses at a higher than average rate. Their disproportionate contribution to the overall delinquency rate garnered great attention, in terms of both research and policy. Although the identification of this group of chronic offenders was important to juvenile justice policy, it is also worth recalling another finding from the Philadelphia study: almost half of the delinquents (46 percent) were one-time offenders and almost two-thirds (65 percent) of the offenders were arrested no more than twice. Similar results were also found in the 1958 Philadelphia birth cohort (Kempf-Leonard et al., 2001).


4 It is also important to bear in mind that there are important methodological differences across criminological studies with respect to who is studied and how. All of this variation can influence the observed results and needs to be kept in mind in interpreting research findings. For further discussion of this, see Box 1-1 at the end of this chapter.

5 There is no clear, generally agreed-upon definition of what it means to be a serious delin quent. Some studies of serious delinquents focus just on the seriousness of the offenses that are committed, some on the frequency of their offending, and others on involvement in violent behavior (Loeber and Farrington, 1998). In addition, some studies focus on the co-occurrence of these dimensions as they tend to be interrelated (Loeber, Farrington, and Waschbusch, 1998; see also Kempf-Leonard et al., 2001). For example, youth who are high-frequency offenders are also more likely to commit violent and serious offenses at a higher rate than others.

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