Rheology, a branch of mechanics, is the study of those properties of materials which determine their response to mechanical force. The word rheology was coined in the 1920’s to represent the science of the deformation and flow of matter, and The Society of Rheology (SoR) was officially formed on December 19, 1929. Meetings of The Society have been held at least annually since that time. The Society has sponsored publication of technical and scientific papers in this field in various journals, currently in its own Journal of Rheology. The Society of Rheology is one of the five founding members of the American Institute of Physics.