The growing concern throughout the world for the logic, the history, and the sociology of science reveals a comprehensive international movement interested in considering the scientific enterprise in its entirety. The purpose of the "International Encyclopedia of Unified Science," as originally conceived by the late Otto Neurath, was to explore in numerous volumes the foundations of various sciences and to aid the integration of scientific knowledge. Circumstances during World War II and the death of Professor Neurath, however, limited the scope of the "Encyclopedia." The Foundations of the Unity of Science constitutes the only completed unit of the proposed multi-volume "Encyclopedia."