Because juvenile homicide is relatively rare, case studies and reports of small samples predominate in the literature. Studies of the association between juvenile homicide and major psychopathology assume that such homicides are so abnormal that some form of major psychopathology must be present. Since variability in diagnostic terminology and diagnostic criteria make comparisons across studies difficult, these studies are discussed using the diagnostic terms preferred by the authors. Episodic dyscontrol in juvenile homicides is a syndrome in which a person with severe ego developmental deficits experiences episodes of severe loss of impulse control. This review concludes that it is tenuous to diagnose psychosis because of the impulsivity and rage of the perpetrator at the time of the homicide. Regarding brain dysfunction in juvenile homicide, the review argues that a well-documented association between homicide and neuropsychiatric symptoms would be only a first step in examining the causal relationship. The overall assessment of the studies is that juvenile homicide is a social and legal construct rather than a scientific one and that multiple factors contribute to the occurrence of juvenile homicides. Methodological suggestions for future research are offered. 87 references.