The absence of universally accepted definitions for direct and indirect assessment motivates the purpose of this article: to offer definitions that are literature-based and theoretically driven, meeting K. Lewin's (1945) dictum that, "There is nothing so practical as a good theory" (p. 129). The authors synthesize the literature to create new definitions of direct and indirect assessment that are evaluated and refined, versus existent literature-based definitions by assessment experts. They conclude by discussing applications of the proposed definitions.