The research aimed to relate the legal theory of competence to stand trial to modern neuropsychological models of cognition. The analysis also focused on whether memory subtypes (episodic and semantic) and social intelligence would have special relevance to these clinical judgments of competence. The participants were 181 individuals who had been committed to Bridgewater State Hospital in Massachusetts during 1987-95; they included 128 individuals recommended as competent to stand trial and 53 individuals recommended as incompetent to stand trial. Multivariate analysis of covariance was used to study group differences on neuropsychological tests. Defendants recommended as competent to stand trial scored significantly higher on summary indexes of psychometric intelligence, attention, and memory than did those recommended as incompetent to stand trial, but they did not score significantly higher on tests of academics or executive function. Moreover, the defendants considered competent scored significantly higher than did the other defendants on selective tests of episodic memory and social intelligence, but not on measures of semantic memory. Partial correlation also revealed a significant relationship between the likelihood of a recommendation of incompetence to stand trial and lower scores on test of episodic memory and social intelligence, but not on measures of semantic memory. Findings illustrated the theoretical importance of neuropsychological methods and concepts to the issue of competence. Table and 58 references (Author abstract modified)