Part I of this chapter develops the concept of adjudicative competence and describes its legal contours. Part II explores youth's participation in criminal trials from a historical perspective, examining whether and how the concept of adjudicative competence has been applied to youths in the past. It also discusses conceptual problems inherent in applying to juveniles the competence criteria currently used in criminal cases and offers suggestions for dealing with these problems. Part III then argues for the application of adjudicative competence in juvenile courts in a limited range of cases. Overall, this chapter argues that juvenile court jurisdiction should be exclusive in cases that involve defendants below the age of 14 at the time of the alleged offense. For cases initiated in juvenile court in which judicial waiver is the applicable mechanism for invoking criminal court jurisdiction, a finding that the juvenile is competent for adjudication in criminal court should be a necessary predicate for transfer. For cases initiated in criminal court, a procedural mechanism for reverse waiver (for the court to decline jurisdiction and transfer the case to juvenile court) should be available for defendants younger than 16 years old. A hearing on the defendant's competence for adjudication should be mandatory in any case that involves a defendant younger than 14 years old. If a criminal court finds that a juvenile defendant lacks the abilities required to understand the proceedings or assist counsel in criminal proceedings, the case should be transferred to juvenile court. In the juvenile court, adjudication should be permitted so long as the juvenile has a basic understanding of the purpose of the proceedings and is able to communicate rationally with counsel. Deficits in the juvenile's ability to appreciate counsel's role or to engage in reasoned decision making should not bar adjudication. 59 notes