Designed for educational planners and decision makers, this report describes the application of mathematical procedures to depict the relationship of elements within models which represent the flow of students through an educational system. The introductory section includes a discussion of the history of the use of planning models in education and the steps in model development (variable identification, identification of variable interconnections, and operationalization and verification of the model). The next section reviews classification schemes for mathematical models of educational processes and presents a classification scheme developed for this report. Following this, examples of several classes of mathematical models of student flow are presented: extrapolation models; regression methods (simple first-order, polynomial, and multiple linear regression); and simultaneous equation models (non-optimizing models including the Markov Chain and optimizing models). Finally, the present utility of available mathematical models is discussed from the viewpoint of what effects these models have had on actual educational policy decision making. (Two related documents are also available in ERIC: Demography and Educational Planning [CE 019 499] and State and Local Responsibilities for Planning Occupational Education [ED 133 479].) (JH)