Criminologists have considered impulsivity one of the most important psychological factors implicated in juvenile delinquency and adult crime. While impulsivity has been widely studied, there is a surprising variance in the conceptualizations of impulsivity. The current study examined the validity of an argument put forth by Whiteside and Lynam (2000) that “there may be four distinct personality pathways through which impulsive behavior may be manifested.” These pathways are lack of premeditation, urgency, sensation seeking, and lack of perseverance. Three samples were used to test the influence of these personality pathways on the manifestation of criminal behavior: a sample of 716 undergraduates enrolled in a large southeastern university, a sample of 481 community members, and a sample of 211 undergraduate students selected based on the results of a screening protocol. The first sample was administered the UPPS Impulsive Behavior Questionnaire; the second sample completed a battery of self-report surveys, including personality measures, and were then administered a laboratory protocol consisting of life history calendars of delinquency and substance abuse and segments of the Diagnostic Interview Schedule; and the third sample completed several laboratory tasks measuring aggressive and impulsive behavior and self-report measures of personality. Results indicate support for the four-factor model of impulsivity proposed by Whiteside and Lynam (2000), and further suggest that the pathways to impulsivity are significant for both men and women. Two of the most important pathways that may manifest in criminal behavior were found to be lack of premeditation and sensation seeking. Future directions for research include an examination of the role of these pathways to impulsive responding. Tables, appendix, references