An invited presentation for the Canadian Operations Research Society, Annual Meeting, Montebello, Quebec, 23 May 1979. The paper is a description of the ISM process, which includes a history of its mathematical "ancestors", with a list of names of the important thinkers who contributed to the mathematical logic supporting ISM theory. The typed manuscript includes copies of slides or transparencies used for the talk. A bibliography lists names of persons currently working with ISM concepts, giving titles of papers on applications, theory of Interpretive Structural Modeling. (The paper includes an Appendix titled `Some Applications of Interpretive Structural Modeling' which was the basis of another talk given by Warfield in November, 1978, in Tokyo at a meeting of the Japan Society of Electrical Engineering and Study Group on Tech. Forecasting.) r.w., circa 2000 This paper was added to the Warfield Digital Collection at George Mason University in 2009