Contemporary historians of education associate the term "social efficiency" with a group of US educators who, in the 1910s and 1920s, aimed at creating a technocratic school and a conservative society of social stability and harmony. However, an investigation of the origin of the term indicates that "social efficiency" began its career in 1894 in the UK with the writing of Benjamin Kidd. From the outset, Kidd's social Darwinist position was disputed by sociologists and philosophers who interpreted the term from a humanitarian point of view. It was the broad, liberal approach inspired by John Hobson, Lester Ward, and John Dewey--and not the narrow, utilitarian approach propagated by David Snedden--that educators took up when they employed the term "social efficiency" to define the main aim of education. (Contains 38 notes.)