The authors analyzed delinquent development from age 12 to 32 in 270 male offenders who underwent residential treatment for problematic behavior and delinquency in a Dutch juvenile justice institution. Stable personality and background characteristics were measured on admission. The development of offending was examined on the basis of conviction data from age 12 to 32, constituting an average 13-year follow-up after release. Trajectory analysis distinguished five groups of serious offenders. Using nonlinear canonical correlation analysis, these offending groups were characterized on personality, behavioral, and background characteristics. Although delinquent activity declined for most juveniles, two groups, high-frequency chronic offenders and late bloomers, showed nontrivial levels of serious criminality until their late 20s and early 30s. High-frequency chronic offenders were characterized mainly by a criminogenic social environment. Late bloomers combined psychopathology with risk-taking behavior and poor social skills. Examining the nature of the offenses committed within each trajectory revealed that late emerging offending became increasingly violent over time. (Contains 4 figures, 3 tables, and 2 notes.)