The analysis is based on data from 13,160 males born in 1958 and residing in Philadelphia between the ages of 10 and 18. The juveniles are tracked over time, and those who had at least one contact with the police are identified. The complete histories of these juveniles are compiled using police rap sheets and investigation reports. An arrest is considered an event that occurs at a given point in time, and event-history analysis is used to model the transition rate from one crime type to another as a function of offense history and offender characteristics. This transition rate encompasses two aspects of the criminal career process: the rate at which arrests occur and the likelihood of transition from arrest to arrest. The analysis indicates that those who have three arrests by the age of 15 will have higher transition rates to additional arrests in comparison with those juveniles who accumulate arrests more slowly. 4 tables, 24 references. (Author abstract modified)