The numerous findings on the development of attachment that have been published in the field of developmental psychology over many decades, along with the attachment theory developed by John Bowlby, are now also being accepted in clinical psychology, psychotherapy and medicine. This handbook sums up the findings on the importance of attachment in various phases of life, as well as the result of clinical research on attachment in relation to psychological and physical disturbances. The special relevance of the theory lies in its fields of application - in prevention and in psychotherapy in various treatment settings.