The flow model in this report is based on the assumption that degree production (output) is a function of the teaching input (number of faculty) but independent of the student input, except in special circumstances. The basic model deals with the flow of people from one stage of education in science to another, from undergraduate to graduate to postdoctoral status, and to professional employment either within the academic world or outside it. The model should be useful in analyzing national educational data and in answering some policy questions. This report also discusses modifications of the basic model in reference to special situations such as national draft policy, and its limitations. Economic inputs, particularly the role of federal funding and its influence on the system, are briefly considered and several policy implications and recommendations for future research are presented. (AF)