This is a theoretical reflection about maternal care in the context of Rooming-in. It is based on Winnicott's concepts of Primary Maternal Preoccupation, Maternal Care, and Good Enough Environment. Rooming-in is conceived as an adequate place for establishing a relationship between mother and child which is favorable to maternal care. While in Rooming-in, the mother lives a peculiar mental status, the primary maternal preoccupation, which goes stronger along pregnancy and is maximal during childbirth. Perceiving Brazilian maternity hospital as a place for care, we see nursing care as an important aid in the interaction between mother and baby, supporting women along this peculiar state of mind.