Nonverbal behaviors play an important role in many social situations, particularly when a communicator is either unable or unwilling to express his feelings explicitly. The concept of repression in psychoanalytic theory, for instance, led to the exploration of nonverbal behaviors as a means of inferring a client’s “unacceptable” feelings. Indeed, psychoanalysts’ early informal discussions of the consequences of repression or reaction formation seemed to provide the impetus for research on nonverbal behavior. The literature on implicit communication provided a basis for developing specific hypotheses for various nonverbal cues associated with deceit. The hypothesis that received some support was that negative affect-indicating cues occur more frequently in deceitful than in truthful communications. The chapter includes three exploratory experiments such as implying truthfulness while conveying ideas consistent or inconsistent with one’s belief, the effects of role-played and actual deceit and behaviors under high motivation to be deceitful.