The objective of this analysis is to address the data and conclusions of Lisa Stolzenberg and Stewart D’Alessio in their article "Co-offending and the Age-crime Curve," published in The Journal of Research in Crime and Delinquency in 2008. The authors analyze National Incident–based Reporting System (NIBRS) 2002 arrests from seven states and conclude that most arrests at all ages involve only one offender, and therefore group offending is of little etiological significance.

To test their claims, we conduct offense-specific analyses of single and multiple arrests using the full 2002 NIBRS arrest data set.

After disaggregating the data by type of offense, we find group involvement among young offenders dominates the arrest statistics for all serious crimes other than rape and aggravated assault. Conclusions: Contrary to the conclusions of Stolzenberg and D’Alessio, co-offending does appear to have a substantial impact on young offenders. The extent of adolescent crime as group behavior may be a cliché in criminological circles, but this is because the empirical evidence for it is substantial.