Studies of children's deceptive behavior have scientific merit and can be carried out in an ethically defensible manner. Many arguments against studies requiring children to deceive others in an experimental context are relatively easy to refute. It is true, though, that the debriefing phase of deception studies presents ethical problems, particularly when the researcher employs a confederate. There are substantial arguments for and against informing children after a study of the nature of any deception incorporated in the research design. Clear ethical problems would exist, of course, if subjects were put in a situation leading them to spontaneously lie or cheat. Two factors support the claim that research on deception is ethical: subjects are at negligible risk, and benefits of the research are high. Further, certain questions can be answered with no other technique. In comparison to results of studies of role-played emotional states, results of deception studies involving spontaneous behavior are more illustrative of skill in the actual use of nonverbal behavior. Recent research suggests that the ability to be deceptive successfully is a social skill related to the development of other abilities in children. The finding of a significant correlation between role-taking abilities and ability to be deceptive illustrates the importance of research in which children are led to be deceptive. (RH)