In criminal careers research, specialization has usually been defined through prespecifying spheres of criminal activity (violent/nonviolent or sexual, violent, burglary, theft, etc.) and then determining the amounts of criminal activity lying within these spheres over a certain time period. However, there is increasing recognition that some offenders work in well-defined domains of offending, which cut across these groups. Thus, some offenders might be involved in both burglary and theft, but unwilling to engage in violent activity, whereas others might also be involved in violence. The authors propose an alternative approach to specialization using latent transition analysis. This approach seeks to identify such domains of activity, which would represent criminal lifestyles. Offenders staying within a domain over time can be defined as lifestyle specialized; those moving between domains are lifestyle versatile. The criminal lifestyles themselves can represent different degrees of diversity. The concept is assessed on England and Wales birth cohort data on female court convictions and comparisons are made with traditional measures of specialization. The authors identify that some females engage in one criminal lifestyle and move to non-offending, others will progress to more diverse lifestyles as they age. Late starters will also tend to engage in diverse patterns of offending.