This paper briefly reviews a variety of perspectives on the structural construct. Included in the review are elements of Freud's thought regarding structure both prior to and after The Ego and the Id. Also included are the ideas of Hartmann, Rapaport, Arlow, Brenner, Gill, and others who have made contributions leading to the preeminence of the structural model. Unfortunately, precisely what is meant by structure is not always clear. Some of the controversies surrounding the meaning of structural concepts seem related to two different usages of the term "structure": one referring to structure in the broad context as a stable organization of various mental elements, and the other referring specifically to the formulations of the tripartite model. From one point of view, the tripartite model constitutes a narrow paradigm within psychoanalysis, specifically applicable to the clinical situation, while the broader concept constitutes a more general scientific paradigm interfacing with similar concepts in ther disciplines.