Affect consciousness refers to the ability to adequately perceive, reflect upon and express affect. The concept is used in clinical work with adults, but lacks an equivalent for children's experience of affect. This paper examines the developmental prerequisites for affect consciousness, as well as the concept's applicability to work with children. The main focus is on the development of affect regulation throughout the first 6 years of life. Special emphasis is put on the role of attachment and the unfolding of mentalization ability in this development. The role of play as an organizing factor for affective experience is discussed. Observation of play is highlighted as a strong indicator of affect consciousness in children.