The legal definition of informed consent is considered in relation to clinical questions that arise when psychoactive medications are prescribed to minors. These clinical questions are numerous and profound: Should informed consent be defined differently for children? Who should give consent? When is consent legal and clinically relevant? How does the physician know when the child has understood and assented? A new theoretical model of informed consent and assent for children is presented, and pertinent legal literature is reviewed. This clinical systems model of informed consent goes beyond simple proxy consent, recognizes different components and levels of consent, and emphasizes the involvement of multiple parties. Particular attention is given to the clinical problems resulting from the influence of multiple persons, the communication between them, the inner understandings of the treatment by the individuals involved, their actions in the treatment, and the change in these factors over time. The impac...