Several previous studies show a relationship between impulsivity and substance abuse; however, it is unclear whether the increased impulsivity seen in substance dependent groups is specifically related to substance abuse, or if it is due to concomitant antisocial personality disorder (ASPD) or aggression. The issue of whether impulsivity is specifically related to substance abuse is important since it has a bearing on risk factors for development of substance abuse. To determine whether cocaine dependent subjects show increased impulsivity independent of ASPD, the Barratt impulsiveness scale (BIS-11), a delayed reward laboratory measure of impulsivity, and the life history of aggression scale were administered to 49 cocaine dependent subjects and 25 controls. Results showed that cocaine dependent subjects with ASPD were more impulsive and aggressive than controls, but cocaine dependent subjects without ASPD were also more impulsive compared to controls. Controlling for aggression history, cocaine dependent subjects without ASPD continued to have elevated impulsivity as measured by the BIS-11, but not the delayed reward task. This study supports the hypothesis that the increased impulsivity as measured by the BIS-11 in cocaine dependent individuals is not exclusively due to concomitant increases in aggression or ASPD.