abstract: The link between childhood neuropsychological deficits and early-onset offending--the assumed precursor to life-course persistent offending--has been well established, yet the underlying mechanisms facilitating this relationship are less understood. Support is growing for the claim that self-control is a key mechanism that links neuropsychological deficits to early-onset offending. Despite this, findings are mixed with regard to the mediating effect of self-control in the relationship between neuropsychological deficits and antisocial behavior. These studies largely support the notion that self-control exerts a mediating effect on neuropsychological deficits when the offending being studied is less serious. Using data from the National Longitudinal Survey of Youth (NLSY), the present study seeks to build upon the existing literature by examining whether self-control mediates the relationship between neuropsychological deficits and two types of early-onset offending--low and high risk--as a means of testing core tenets of Gottfredson and Hirschi's (1990) and Moffitt's (1993) criminological theories. Findings show that while self-control and neuropsychological deficits independently predict general early-onset offending, these effects vary as a consequence of early-onset offender type. The results point to the need for future research to explore the possibility that the early-onset offender group that leads to persistent offending could be more precisely defined. Examining early-onset offending as a single construct limits our ability to make inferences about those offenders that are the most persistent in their offending patterns and, arguably, more likely to continue offending over the life-course. / Dissertation/Thesis / M.S. Criminology and Criminal Justice 2014