The fundamental premise of this book is that assessment and therapeutic communication with children, parents and young people does not commence with the uncovering of pathology, but with the understanding of the meaning of their behaviour. This necessitates, ®rst and foremost, that we have a grasp of the foundations of normal child and adolescent development. All children and young people, in whatever situation they ®nd themselves, share the experience of being born, of being dependent, of forming relationships with the important people in their lives and of having to meet the tasks of the different developmental stages as they progress from infancy through to adulthood. A focus on development enables us to identify what constitutes the unifying experience for all children and young people, rather than what sets them apart from each other. The recognition of a unifying developmental experience for children and young people leads us in turn, as professionals, to be able to assert a set of unifying principles that inform practice and that can lead to more productive and enduring therapeutic outcomes.