Objective: The purpose of this study was to determine whether life-course-persistent (LCP) and adolescence-limited (AL) antisocial behavior form distinct categories or lie along a common dimension. Method: Taxometric analyses were performed on 2,175 men and women from the National Longitudinal Survey of Youth-Child Data (Center for Human Resource Research, 2009) with at least 1 self-reported delinquent act. The 3 externalizing factor scales from the parent-rated Behavior Problems Index (Peterson & Zill, 1986)--Antisocial, Headstrong, and Hyperactive--served as indicators in an investigation into the latent structure of LCP and AL antisocial behavior. Results: All 3 taxometric procedures included in this study--mean above minus below a cut, maximum covariance, and latent mode factor analysis--produced results consistent with the conclusion that the latent structure of LCP and AL antisocial behavior is dimensional in nature. Conclusion: From a conceptual standpoint, the results of this study suggest that LCP and AL antisocial behavior differ in degree (quantitative difference) rather than in kind (qualitative difference). These results have potentially important implications for theory development as well as for clinical assessment, diagnosis, and intervention. (Contains 2 tables and 3 figures.)