This authoritative text is a must-read for anyone working, or training to work, with young people. It considers how theory, policy and practice intersect and influence one another in today's challenging and rapidly changing social, economic, and political contexts. Offering a timely contribution to the debate, it covers key themes and developments, including the principles that underpin work with young people, the policy and practice in a wide range of contexts, both national and international, the key concepts currently high on the policy and practice agenda, and how we understand the lives of young people, in particular investigating their 'real worlds' and understanding their social construction.