This article juxtaposes psychoanalytic thought with recent infant research toward an understanding of the range of meanings of the term mental representation. A definition of mental representations as unconscious organizing structures of interactions is proposed as a comprehensive integration of the various points of view on this issue, incorporating the traditional psychoanalytic view of representations as well as those revisions suggested by extensions of theory within psychoanalysis and developmental research. An overview of traditional psychoanalytic thought on representations is presented as is a review of later contributions. Several points of divergence between the two bodies of thought are discussed, including the issue of self-object differentiation, the caretaker-child dyad as the focus of analysis, and the capacity within the first year for emergent structures which allow the infant to develop interpersonal expectations. The influences of Piaget's theory of representation on each body of thought are also addressed.