The case of a four-year-old boy with a postural symptom that resolved rapidly in the course of play therapy is presented. Various unconscious fantasies appeared to underlie the symptom. In particular, this case illustrates a young child's sophisticated capacity to abstract a complex relational feature from a set of unconscious fantasies that then became the basis of his symptom. The structure of the boy's symptom is relevant to (1) the question of what constitutes a symptom, (2) the relationship between concept development and symptom formation, and (3) the status of certain primary process mechanisms as they relate to concept development. Proposals are presented to help situate the contributions of psychoanalytic theory with respect to the domain of cognitive psychology, and to illustrate the unique contributions of each domain toward their mutual enrichment.