The research included a sample of 500 urban male delinquents age 11 to 17 and 500 urban male nondelinquents age 11 to 17 matched case by case on age, race/ethnicity, IQ, and neighborhood socioeconomic status over a 25-year period. The Gluecks' research team gathered information for these 1,000 men with respect to crucial social, psychological, and biological factors; changes in relevant life events; and crime patterns as measured by both official records and personnel interviews. The participants were originally interviewed as juveniles, at age 25, and at age 32. The analysis revealed only modest indications of crime specialization and no clear evidence of escalation. Results indicated that juvenile and adult offending are diverse enough to make prediction of the next type of offense somewhat difficult. Because the next offense will probably be a property offense, it is difficult to predict violent criminality accurately. In addition, no consistent pattern exists indicating a direct effect of juvenile justice sanctions on subsequent crime. Nevertheless, a followup of official criminal records and death records for the Glueck men would be both feasible and useful. Tables, list of related publications, and 10 references