This article examines the function of play in normal development and within the treatment relationship in both child and adult psychotherapy. Noting its developmental function and the natural role that play has as a mode of communication with children, the author emphasizes the centrality of play in the construction of the therapeutic alliance. The therapeutic alliance is characterized here as a libidinal attachment, a new object relationship through which developmental experiences involving play may be revivified and, ultimately, may lead to the forging of more enduring and successful adaptations. Two detailed clinical vignettes furnish illustrations of the ways in which play themes and scenarios develop in therapy, and how their association to the therapeutic alliance and transference relationship may be understood and interpreted.