We come now to one of the main aims of this book: an attempt to describe Attachment Theory’s distinctive contribution to the theory and techniques of psychotherapy in practice. Two related concepts have emerged. The first, starting from Object-Relations Theory, but going beyond it, is the idea of the core state with respect to attachment. Bowlby saw a person’s attachment status as a fundamental determinant of their relationships. Whether smoothly functioning or problematic, core attachment patterns have a powerful influence on the way someone sees the world and their behaviour. When there is a secure core state, a person feels good about themselves and their capacity to be effective and pursue their projects. When the core state is insecure, defensive strategies come into play.