The rationale for the Planning, Monitoring, and Implementation Model (PMI) is the subject of this paper. The Superintendent of the District of Columbia Public Schools requested a model for systematic evaluation of educational programs to determine their effectiveness. The school system's emphasis on objective-referenced instruction and testing, performance-based teacher assessment, and administrative accountability required goal-attainment or objectives-oriented models with clear descriptions of existing conditions and outcomes and with emphasis on observation and monitoring. The approaches of Robert E. Stake and Malcolm Provus provided the basic strategies for the PMI model developed by the Division of Research and Evaluation. The model provides for both ongoing evaluation to improve the program and final evaluation to determine the worth of a program after it has been completed. Finally, the model is designed so that conclusions and implications of the evaluation can be related to decisions being made. (Author/MLF)