For both the Aboriginal and non-Aboriginal subsamples, two groups were identified that differed statistically in terms of the parameters of the growth-mixture model (i.e. initial levels of offending and rates of progression in offending over time). Although a small proportion of the offenders exhibited serious and persistent offending over their life-course, the majority of the juvenile probationers engaged in relatively less frequent and/or serious criminal activity over time. The size of the chronic high-offending trajectory groups was slightly larger among Aboriginal offenders (18.7 percent) than among the non-Aboriginal offenders (12.3 percent). These findings differed with the outcomes of recent empirical studies that suggested the presence of more than two distinct offending trajectory groups. The detection of only two groups of offenders in the current study was also contrary to expectations. The discrepancy in findings between the current study and past research could be attributed to methodological and analytical differences. Specifically, the current study may have overestimated the differences in serious-offending and persistent-offending trajectories between the two groups. Additional analyses found that the Aboriginal offenders were more likely to come from an impoverished background, characterized by an unstable familial environment, substance use, and negative peer associations. In contrast, accommodation problems predicted the increased likelihood of being in the chronic high group of the non-Aboriginal offenders. In drawing implications from these findings, this study suggests that chronic high offenders receive multifaceted cognitive-behavioral rehabilitative interventions that include social-skills training and teacher support. Findings also suggest that resources be invested early in the course of development. 4 tables, 1 figure, 15 notes, and 75 references