This part introduction presents an overview of the key concepts discussed in the subsequent chapters. The part considers how to understand and assess adolescents in the light of their potential for changing the way they relate to significant people in their lives. It focuses on assessing and understanding the foster family as a system. The book considers some common difficulties between members and subsystems of the wider caregiving network which includes the adolescent and foster family members. The aim of interaction with adolescents showing a pattern of emotionally detached behaviour is to encourage and enable the adolescent to test themselves out in less distanced interaction. The process of verbal feedback to the adolescent relating to the impact of their behaviour and what are the likely consequences of it, becomes an important way of challenging obsolete internal working models of self as a helpless victim of circumstances, or as totally unlikeable.