Contemporary literature on mechanisms, particularly in analytical sociology, assumes that the concept of mechanism rests upon the idea of causality. The article investigates the origin of this association through the analysis of classical texts of four mathematical sociologists from the 50's and 60's—Coleman, Fararo, Karlsson, and Simon. The first part shows that the recent literature on mechanisms holds the “generative” view of causality as expressed by some realist philosophers of science in the 60's. The second part argues that the use of the concept of mechanism implies the idea of causality in mathematical sociology, as well as an adhesion to the principle of methodological individualism. By way of conclusion, the article emphasizes the similarities between early mathematical sociology and contemporary analytical sociology.