This book has been a long time in the writing. One reason is that it began life as something else. I wanted to investigate the age at which children started work in the era of industrialization, and searching for a source of information that could track back into the eighteenth century, I stumbled on writings by working men in which they reminisced about their first jobs and the reasons for their entry into the labour force. I decided to search the now extensive body of known working-class autobiography and extract quantitative information on age at starting work, first jobs and so on, a laborious task to be sure but using a source which promised to provide information about individuals and span the now elongated era of industrialization and therefore of great value. A deeper interest has always been the interface between the family and the economy: how the family both responds to economic opportunities and moulds economic development. Children stand side by side with women at this margin. This ambiguous position has governed children's meaning and importance as they have made the transition from contributors to family resources and social insurance for parents to the expensive luxury consumption goods that they constitute today. Historians have neglected children's metamorphosis yet it is surely one of the social and economic revolutions of modern times, though here again, as the dismal catalogue of recent cases of appalling abuse makes clear, even in rich economies with well-developed welfare states not all children have managed to become the ‘priceless’ possessions that modernity promises.