In celebration of its anniversary, 125 Years: The Physical Society and The Institute of Physics charts the history of the Institute from its origins to the present day. It provides a fascinating account of the people and events that shaped the Institute's development and includes the emergence of physics as a separate scientific discipline, the formation of the Physical Society of London, the establishment of the Institute of Physics, the granting of a Royal Charter to the Institute of Physics, and the final decades of the millennium. Separate chapters are devoted to the educational, professional, and publishing activities of the Institute.