Helping both parents and psychologists to arrive at a better understanding of the inner emotional world of the infant, this selection of key lectures by Bowlby includes the seminal one that gives the volume its title. Informed by wide clinical experience, and written with the author's well-known humanity and lucidity, the lectures provide an invaluable introduction to John Bowlby's thought and work, as well as much practical guidance of use both to parents and to members of the mental health professions.