Across a variety of data sources, countries, cities, and time periods, researchers have consistently documented the existence of a chronic offender. Such offenders comprise a small percentage of cohort members, but are responsible for a large proportion of criminal offenses, including violent offenses. This research has provided useful descriptive information on criminal careers leading to the development of theoretical accounts and controversial public policies, though there are two limitations of this line of research. The first is the highly skewed distribution of offending rates. The second is that little is known about the existence of the chronic female offender. The present research attempted to overcome these limitations, using data from the Philadelphia Collaborative Perinatal Project (CPP) Birth Cohort, in an effort to provide descriptive information on whether chronic offenders are the most serious offenders, and the extent to which the relationship between chronicity and seriousness is invariant across gender. In addition, this research used a measure of offense skewness that allows for meaningful comparisons of offense skewness both within and across data sources. The results suggest that: (1) a small group of offenders is responsible for a large proportion of the offenses, and (2) relative to one-time and recidivist offenders (2-4 offenses), chronic offenders (5+ offenses) are more likely to display an early onset of offending as well as participate in violent offending. These two results were invariant across gender. When examining measures of offense skewness, the results suggested that, while the Philadelphia CPP had slightly lower offense skewness than the 1958 Philadelphia birth cohort, males had higher offense skewness compared to females. Implications for future research were also addressed.