The author examines the developmental underpinnings of imagination and explicates the process by which the child's fantasy life becomes weakly connected to reality. Using theories of attachment and mentalization, the author argues that the repeated experience of severe and abrupt disconnection from the parent as a result of her unpredictable and frightening behavior may interfere with the development of the child's fantasy life. Two likely outcomes are put forth as a result of this sudden disconnection. The first outcome is one in which the child retreats into a fantastical cocoon that is divorced from the interpersonal world around him. In the second outcome, the patient's mental life is bereft of imagination and fantasy such that rationality, logic, and concreteness contribute to an affectively impoverished inner life devoid of novelty and surprise. Clinical vignettes are used to illustrate these developmental outcomes as well as an extended adult case that highlights the developmental origins of the patient's private fantasy life and the therapist's attempt to facilitate its linkage with the interpersonal sphere of experience.