This third volume, entitled *Hatred in Countertransference: Writings on Deprivation and Childrearing and Notes on the Transitional Object (1946-1951)*, continues the publication in Spanish of the *Complete Works* of Donald W. Winnicott. The *Complete Works* have been compiled, edited, and annotated by a team of Winnicottian scholars. Presented chronologically in 12 volumes, the English psychoanalyst's *Complete Works* comprise a collection of clinical observations, consultations with children, psychoanalytic texts, correspondence, and previously unpublished works on topics that remain relevant to contemporary readers (such as childhood mental health, motherhood, and his concepts of the "good enough mother" and the "transitional object"). This third volume includes an introduction by Vincenzo Bonaminio and Paolo Fabozzi, as well as an introduction by the Spanish translation committee. Likewise, the reader will have access to exhaustive notation and commentary by the editors, which provide context for each of Winnicott's works, in conjunction with the notation work done by the translation committee, which marks the choice of certain concepts over others in our language.