"Informed consent" is the voluntary agreement of an individual, or his or her authorized representative, who has the legal capacity to give consent, and who exercises free power of choice, without undue inducement or any other form of constraint or coercion to participate in research. "Ethics and Regulations of Clinical Research." New Haven: Yale University Press, 1988.) "Assent" is a term used to express willingness to participate in research by persons who are by definition too young to give informed consent but who are old enough to understand the proposed research in general, its expected risks and possible benefits, and the activities expected of them as subjects. If assent is given, informed consent must still be obtained from the subject's parents or guardian.In addition, there are a number of procedures for which separate consent or assent must be given, usually just before proceeding, even though they have been detailed in the earlier-signed agreement to take part in the protocol.These procedures include general anesthesia, endoscopy, marrow aspiration, lumbar puncture, and HIV testing.In general, research participants give informed consent after discussing the protocol with the PI, or others as appropriate.