This book offers an historical analysis of an area of young people's activity which remains significant in the present. It shows that many thousands of young people in England were involved in peace movement activity from 1919 to 1969, in connection with the League of Nations Union before the Second World War, pacifist bodies like the Peace Pledge Union in the 1930s and 1940s, the Council for Education for World Citizenship post-1945, and the Campaign for Nuclear Disarmament from 1957. Young people engaged with the peace movement at school, at home and in the community, encompassing classroom learning, attending lectures and meetings out of school hours, pageants, international camps and visits, correspondence, and sometimes demonstrations, marches and other direct action protests. Some were engaged briefly, for others this became a long-term focus of time, energy, and ideological commitment. Some followed parents, teachers, and friends. Others rebelled against those around them. Examining the perspectives of those involved as young people, and the adults aiming to involve young people in the peace movement, this book is an important addition to our knowledge about movements and activism (in the peace movement and more broadly), and to our knowledge about young people's agency and its limits.