The starting point for the design of this study was a National Institute on Drug Abuse (NIDA) investigation entitled "Drug-Related Gang Violence in South Texas," which examined the epidemiology of violence and drug use among male members of 26 gangs in San Antonio, Tex. The purpose of the NIDA study was to identify and distinguish the relationship of gang violence, illicit drug use, and high-risk sexual behavior. A supplementary, cross-sectional, descriptive study was designed to measure psychopathy in a random subsample of 50 gang members and a matched comparison group of 25 males. The findings of this supplementary study are provided in this article. Analysis involved t-test, chi-square, and Cronbach's alpha statistics. More than half of the gang sample were categorized as low, 44 percent as moderate, and only 4 percent as high on psychopathy. The gang members had higher scores on the total, affective, and behavioral scores than the non-gang members. High scores on adolescent antisocial behavior, poor behavioral controls, and lack of remorse were found in both samples. Gang members scored twice as high as non-gang members on lack of empathy. Both samples were lower on psychopathy than the forensics and higher than psychiatric patients and undergraduates. The results provide grounds for early intervention efforts for this high-risk population. 2 tables, 2 figures, and 30 references