One of the many exhortations to children to help with the war effort was issued by the Ministry of Information in 1941; its opening paragraph is our opening quotation and its title, which we have borrowed for this book, is ‘You Can Help Your Country’. In the book, we address a neglected topic that is, nevertheless, a part of the history of childhood in twentieth-century England. We focus on children’s work during the Second World War, and in particular the contributions that children made to the war effort. The topic may have been neglected because another subject has – perhaps understandably – dominated discourse on children in the war years: evacuation. Indeed, when we have mentioned the words ‘children’ and ‘the war’ to people as an introduction to explaining what our book is about, they immediately assume that we are interested in ‘evacuation’. Many people have stories to tell about evacuation and it was indeed a huge social upheaval, with about 1.5 million children affected in September 1939. Further movements of children, parents and teachers took place during periods of intensive enemy action (autumn 1940, summer 1944). But the story we shall tell in this book is of a parallel set of events whereby children of all ages, whether evacuated or not, were encouraged to take part in the war effort, and we shall also detail what work they did.