Understanding the progression of violent and nonviolent criminal activity remains a matter of theoretical debate. In the present study, the authors build on criminological theory and assess the extent to which the progression of violent and nonviolent criminal behaviors follows different trajectories. The authors rely on semiparametric mixture models to examine these comorbidities of offending in a longitudinal sample of delinquent adolescents. The results suggest that the trajectories of violent and nonviolent criminal offending follow similar paths over time and that membership in the chronic violent and nonviolent offender groups are associated with overlapping sets of risk factors. However, the results also indicate that at the individual level, membership in a particular nonviolent offending group does not share high concordance with membership in a particular violent offender group. These findings raise questions about the adequacy of general theories of crime progression and suggest the need to continue investigating behavioral theories that discriminate between different forms of offending. (Contains 3 figures, 8 tables, and 17 notes.)