Interpersonal deception theory (IDT) represents a merger of interpersonal communication and deception principles designed to better account for deception in interactive contexts. At the same time, it bas the potential to enlighten theories related to (a) credibility and truthful communication and (b) interpersonal communication. Presented here are key definitions, assumptions related to the critical attributes and key features of interpersonal communication and deception, and 18 general propositions from which specific testable hypotheses can be derived. Research findings relevant to the propositions are also summarized.