This paper explains the concept of models, their construction, and their use. It is suggested that mathematics is a helpful tool in model construction, and that models in general are indispensable in science. Models identify variables and illustrate causal relationships among the variables. An attempt is made to classify models from the point of view of the problems they attempt to solve. Included are the construction, verification, and application of mathematical models in pure science, case studies, and policymaking. A description and classification of the mathematical models available for educational planning are presented. In the final section is a brief description of the basis for the conflict between those who advocate and those who oppose the use of models. A 56-item bibliography on mathematical models of education is included. (MLF)