This book is not concerned with innovation in basic psychoanalytic concepts or techniques, but with the formulation and testing-out of ideas whose origin was in the challenge of day-to-day clinical work that was the staple of Winnocott's medical experience throughout his professional life. This book is arranged in three sections. The first represents Winnicott's attitudes as a pediatrician prior to training in psycho-analysis, and demonstrates the degree to which a purely formal pediatric approach requires as an effective complement a deeper understanding of the emotional problems of child development.