Humanists have been a major force in British life since the turn of the 20th century. Here, leading historians of religious non-belief Callum Brown, David Nash, and Charlie Lynch examine how humanist organisations brought ethical reform and rationalism to the nation as it faced the moral issues of the modern world. This book provides a long overdue account of this dynamic group. Developing through the Ethical Union (1896), the Rationalist Press Association (1899), the British Humanist Association (1963) and Humanists UK (2017), Humanists sought to reduce religious privilege but increase humanitarian compassion and human rights. After pioneering legislation on blasphemy laws, dignity in dying and abortion rights, they went on to help design new laws on gay marriage, and sex and moral education. Internationally, they endeavoured to end war and world hunger. And with Humanist marriages and celebration of life through Humanist funerals, national ritual and culture have recently been transformed. Based on extensive archival and oral-history research, this is the definitive history of Humanists as an ethical force in modern Britain.