The study used a two-dimensional analysis of aggressive behavior. As criterion variables, it used a self-reporting dyscontrol scale, which included 18 statements selected by Plutchik and drug-activated generalized theta activity, which correlated significantly with subcortical seizural activity and central nervous system instability. A total of 93 relatively unselected aggressive criminal subjects were assigned to 4 groups. Group 1 was characterized as high theta and high dyscontrol; group 2 manifested high dyscontrol but low theta; group 3 had high theta activity but a low dyscontrol score; while group 4 scored low on both theta and dyscontrol measures. These groups were labeled epileptoid, hysteroid, inadequate, and normal, respectively. The epileptoid dyscontrol group appeared more sexually active and perverse both in the prison setting and in their past lives and tended to be more energetic and active. Except for group 1, group 3 showed the most outstanding deviations and was differentiated from all other groups in terms of irresponsibility and poor judgment. The clinical validity of this study will ultimately be determined by the therapeutic effectiveness of a regimen based on the data. Two tables, five figures, and nine references, are supplied.