This chapter begins by laying out the fundamental principle that children and young people’s behaviour always has function and meaning and that working to make sense of it is the foundation of all effective helping strategies. A dynamic developmental approach is elaborated to support understanding of how young people’s way of seeing themselves, the world around them, perceiving threat, and understanding and managing emotions and relationships are shaped up by significant adults and life events. This framework is used to develop understanding of how problems and disruptions in this developmental process can leave young people struggling to control their feelings and at risk of relationship problems, aggression, and challenging coping responses. The pivotal role of non-mental health specialists who come into contact with young people in their every days lives is explored, including principles and tips for effective engagement, early help, and risk reduction. Guidance is provided on how to identify young people who need more specialist assessment and help and what this help should look like, in accordance with clinical guidelines, using a case study to bring this to life. Finally, the complex relationship between emotional and behavioural regulation difficulties in adolescence and adult personality disorder diagnoses is discussed. Common misconceptions and challenges that need to be overcome, to ensure our young people get the help they deserve to improve their life changes and health outcomes and they navigate the transition into adulthood, are explored.