The Viennese-born polymath Otto Neurath died on 22 December 1945 in Oxford, a few months after the end of World War Two. A social engineer and sociologist of happiness, Neurath was not only a socially sensitive educator, advocating for any institute and organization that was concerned with the well-being of people; he was also a trained scientist and philosopher. Studying mathematics, economics, history, philosophy, and physics in Vienna and then in Berlin during the early years of the long twentieth century, Neurath became involved in many of the disputes among social and natural scientists that shaped the course of the fields. This short introduction provides the context and describes the aims of the volume. Short summaries of the chapters are also included.