Competence to stand trial is a legal construct used to identify those criminal defendants who have the requisite mental capacity to understand the nature and objective of the proceedings against them and to participate rationally in preparing their defense. This Practice Guideline has described how psychiatrists should evaluate individuals concerning their competence to stand trial. The Guideline describes acceptable forensic psychiatric practice for such evaluations. Where possible, it specifies standards of practice and principles of ethics and also emphasizes the importance of analyzing an individual defendant's case in the context of statutes and case law applicable in the jurisdiction where the evaluation takes place. The recommendations in the Guideline both reflect and are limited by evolving case law, statutory requirements, legal publications, and the current state of psychiatric knowledge. The authors have taken note of nationally applicable case law, federal constitutional standards, statutory language, and federal and state interpretations of the rights or statutes, recognizing that jurisdictions may differ in their specific interpretation or application of statutes or general constitutional standards. The review of cases concerning specific psychiatric diagnoses illustrates general U.S. trends, and psychiatrists must remain cognizant of their jurisdictions' interpretations of statutes or constitutional requirements. By surveying a variety of practices and approaches to data gathering and case analysis, the authors believe that this Guideline will stimulate additional collegial discussion about what is necessary and sufficient for adequate evaluations of adjudicative competence. The notion that psychiatrists should apply expertise to competence assessments stems from the principal that, before allowing a defendant to face criminal prosecution and possible punishment, courts need reasonable assurance--based, if necessary, on a careful, individualized evaluation--that the defendant has adequate mental capacity to make a defense. At a minimum, a psychiatrist's opinion about adjudicative competence should reflect an understanding of the jurisdictional standard and of how the defendant's mental condition affects competence as defined with the jurisdiction. The psychiatrist's report should clearly describe the opinion and the reasoning that leads to it. Psychiatrists who provide mental health expertise concerning adjudicative competence give trial courts information needed to assure that defendants can appropriately protect themselves and that criminal proceedings will be accurate, dignified,and just.