One area of social life with considerable importance for the exercise of power over children is informed consent. The question posed here is whether children should be permitted to make decisions that authorize their participation in research and/or their receipt of medical care, or whether someone else should make those decisions on their behalf, namely a parent or someone charged by the state with acting in a parent's absence. Adults are permitted to make informed consent decisions when they are judged competent to do so, and this paper will explore children's competence to make informed consent decisions. In defining competence, some give priority to the capacity for autonomous self-determination while others prioritize the capacity to make decisions that will promote one's well-being. However, conflicts may arise between the judgment that we ought to respect children's autonomy and the judgment that we ought not do so but rather promote children's well-being. If such moral dilemmas can arise in deciding whether children are competent, it follows competent persons are able to perceive when moral judgments come into conflict and when such a conflict presents as a moral dilemma, and are prepared to deal with, and are capable of dealing with, such a conflict. It is also argued that competence is not an all-or-nothing category but rather admits of differences in degree and, in particular, children's capacity for competence evolves and develops. Also, although the exercise of parental authority in most cases is a limit on children's voluntariness, it can be exercised in such a way as to promote children's competence. It will be argued here that authoritative parenting can provide opportunities for joint decision-making between parents and children and in that way can promote the development of children's competence. The implications for the laws and policies of the state are significant. The argument of this paper suggests the state should support children's rights to make informed consent decisions and also should require that parents support their children's free and informed decision making.