Introduction : the problem of youth crime -- Children, young people and modernity -- From justice to welfare and its malcontents -- Youth justice and the new conservatism -- New Labour and the youth justice system -- Theorising the development of youth justice -- Youth offending as rational behaviour -- Biological explanations of youth offending -- Psychological explanations of youth offending -- Sociological explanations of youth offending -- The coalition, the big society and youth justice policy -- The contemporary youth justice system -- Effective youth justice in practice -- Youth justice in wider context -- Comparative youth justice -- Conclusions : the future of youth justice.