A multimethod, multisource assessment of impulsivity was conducted in a sample of more than 400 boys who were members of a longitudinal study of the development of antisocial behavior. Exploratory and confirmatory factor analysis of the 11 different impulsivity measures revealed two impulsivity factors: Cognitive and Behavioral. Cognitive and behavioral impulsivity had similar correlations with socioeconomic status. Cognitive impulsivity was more strongly related to IQ than was behavioral impulsivity. Behavioral impulsivity was more strongly related to delinquency at ages 10 and 12-13 than was cognitive impulsivity. Consistent with theoretical prediction, our results also indicate that behavioral impulsivity was especially related to serious delinquency that is stable over
time.