A model for forecasting postsecondary enrollment, the PDEM-1, is considered, which combines the traditional with a cross-pressure impact decision-making model. The model is considered in relation to its background, assumptions, survey instrument, model conception, applicability to educational environments, and implementation difficulties. The model has been subjected to three years of research, development, validation, and external evaluation. The survey instrument consists of two instruments designed to follow the student's decision-making and assess dimensions of change and reasons for change occurring since the last contact. Academic and occupational plans, family influence and background, financial situation, and summer plans before college entry are among the areas tapped by the survey instrument. The model includes a pure demand report, which represents students' intentions to enroll in postsecondary education, and actual enrollment forecasts, which represent those students anticipated to persist in spite of constraints, such as academic eligibility. The model can review enrollment outcomes by institution and program as decision-making variables are changed. The following concerns relating to application of the model are examined: costs and benefits, budgeting, program planning, comprehensive educational planning in a transitional environment, representativeness of the sample, systems level application, size and accuracy, and full-time students. Implementation problems are also considered. (SW)