The design of the Planning, Monitoring, and Implementation Model (PMI) and the aspects of the model that make it useful in public schools are the topics of this paper. After the objectives of a program or operation have been identified, the model specifies three additional pieces of information that are needed for an evaluation: inputs, processes, and outcomes. These aspects of a program can be further classified either as intended or observed, depending upon a given point in time. Several kinds of analyses are possible as a result of the data-gathering process. The first analysis, "monitoring," seeks to determine the degree to which intentions were actually realized by examining inputs, processes, and outcomes. Analysis of the monitoring data can result in agreement or discrepancy. The second analysis, "performance agreement," involves determining the degree to which observed inputs affected observed process, and observed process affected observed outcomes. The application of the model provides for both ongoing evaluation, which serves to improve the program (formative), and final evaluation of a program in order to determine its worth after it has been completed (summative). Decisions to revise, continue, or terminate a program can result from the systematic process of data collection and analysis that the model requires. (Author/MLF)