In the past three decades competency to stand trial has emerged as a central issue in mental health law and forensic psychology. This article combines legal and clinical frameworks for a more integrated understanding of competency to stand trial. The legal framework focuses on Supreme Court decisions beginning with Dusky and reviews several legal theories of competence. The empirical framework is investigated within Grisso's (1986) conceptualization of legal competencies. In addition, the efficacy of specialized forensic assessments is evaluated, including the newly developed MacArthur Structured Assessment of the Competencies of Criminal Defendants (MacSAC-CD). The article concludes with observations of competency as a construct and their implications for forensic practice.