A hypothetical mathematical model of a school is presented to (1) illustrate what such a model would look like, (2) determine its value to decision makers, and (3) determine its data requirements. The model relates increases in achievement to student/staff ratio, a measure of staff quality, materials used, space available, effort in community relations, and the socioeconomic background of students. The relationship is nonlinear. The model is illustrated numerically by use of hypothetical data. Use of the model in a search for optimum school resource allocation is discussed briefly, and further developments are outlined. (Author/DE)