In this paper, the author attempts to arrive at a comprehensive outline of Winnicott's developmental theory. This theory encompasses the infant's emergence from total dependence and subject/object merging to what the author refers to as relative independence and relative subject/object separation (in Winnicott's words, “separation that is a not a separation but a form of union” [1971a, p. 98]). This conceptualization is based mainly on an amalgam of Winnicott's two well-known papers, on transitional objects and phenomena (1953) and on the use of an object (1969). The author also refers to André Green's notions of the importance of the negative and of the “dead mother” in reference to Winnicott's work. To demonstrate the clinical implications of the paper, the author discusses in detail the case of Rosemary Dinnage, as described by both Winnicott and Green and as reported directly by herself.