Do those males experiencing an early onset of offending commit more crimes over time than their later-onset counterparts? This is a question that is central to several contemporary developmentally based criminological theories. For example, it may be that both individual offending frequency and offense seriousness increase with age and peak at a higher level for early-starters. That is what some developmental theorists would argue (see Loeber and Hay, 1994; Moffitt, 1993), presumably because early onset is an indicator of a more severe tendency toward delinquency and criminal activity.

In official and self-report records, early onset predicts a relatively large number of offenses in total (Farrington et al., 1990; Le Blanc and Fréchette, 1989). Using official records, several studies show that individual offending frequency is approximately constant after onset (Farrington et al., 1998:101; Hamparian et al., 1978:60l; Tarling, 1993:57). Across individuals, Tolan and Thomas (1995) and Krohn et al. (2001) showed that the frequency of offending in self-reports was greatest for those with the earliest ages of onset. Recently, Farrington et al. (2003), using data from the Seattle Social Development Project, investigated how strongly an early age of onset predicts a large number of offenses (in total and per year) in self-reports compared with court referrals. Their findings indicated that an early age of onset predicted a large number of offenses in both self-reports and court referrals.