Since children are considered incapable ofgiving informed consent to participate inresearch, regulations require that bothparental permission and the assent of thepotential child subject be obtained. Assent andpermission are uniquely bound together, eachserving a different purpose. Parentalpermission protects the child from assumingunreasonable risks. Assent demonstrates respectfor the child and his developing autonomy. Inorder to give meaningful assent, the child mustunderstand that procedures will be performed,voluntarily choose to undergo the procedures,and communicate this choice. Understanding theelements of informed consent has been theparadigm for (...) assessing capacity to give assent.This method leaves the youngest, leastcognitively mature children vulnerable towaiver of assent and forced researchparticipation. Voluntariness can also becompromised by the influence of authorityfigures who can exert undue influence andcoerce children to participate in research. This paper discusses factors that may influencethe decision to give assent/permission,potential parent-child conflict in theassent/permission process and how it isresolved, and potential parental undueinfluence on research participation. Theseissues are illustrated with quotations drawnfrom a larger qualitative study of parentalpermission and child assent (data notpresented). We suggest a developmentalapproach, viewing assent as a continuum rangingfrom mere affirmation in the youngest childrento the equivalent of the informed consentprocess in the mature adolescent. (shrink)