The rise of postwar youth cultures made young people a problem for many adults and an issue for academics. Biologists, sociologists, criminologists, psychologists, psychiatrists and educationalists have compiled an immense literature. Youth research is a well-established social-science industry that has been sliced into specialisms. There are experts on young people and education, the family, work and delinquency, but writers on all these topics recognise that the behaviour on which they focus – criminal, educational, vocational or sexual – is influenced by the youth cultures in which adolescents become involved. Investigators who have studied Teddy Boy, rocker, mod, punk and skinhead cultures have therefore not been carving out another specialism so much as trying to synthesise and generate a total understanding of young people’s lives and values. Students quickly learn that in this, as in so many other fields, the experts are divided, and the main divisions are not all tidily organised along subject boundaries. Competing theories within subjects, especially sociology, have bred fiercely disputed interpretations of youth cultures. There has never been one proven and generally accepted theory explaining the significance of postwar developments among young people at leisure. Nor will there be, until the properties of leisure are taken fully into account.