Discusses the cognitive and behavioral characteristics of minors in relation to the question of competence to consent to treatment. The legal standard (knowing, intelligent, and voluntary) used to judge the effectiveness of consent is translated into psychological concepts, especially cognitive abilities. A review of developmental psychological research is presented, which examines these concepts as they relate to minors' abilities to satisfy the legal standard. It is suggested that cognitive developmental stages associated with ages below 11–23 yrs might exclude such minors from meaningful consent. In addition to cognitive considerations, certain results suggest that the tendency toward deference in early adolescence is so normative that capacity for voluntary consent is questionable through age 14, but existing evidence provides no psychological grounds for maintaining the general legal assumption that minors at age 15 and above cannot provide competent consent. (63 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)