The literature on the practice of educational evaluation is reviewed, and internal and external evaluations in a school setting are compared. The paper states that the typical external evaluation is conducted as if school districts were rational organizations, a view which permeated 19th century evaluation activities. The internal evaluator, on the other hand, has a view from the inside, making it possible to see first hand the complex, somewhat disorderly environment of a school system. Evaluation was introduced into educational administration in the middle of the 19th century. However, when the collection of facts failed to solve the problems of education, educational administrators became disillusioned. Evaluation was limited primarily to the assessment of individual student achievement from the 1930s until the 1970s. The advent of federally-funded instructional programs in the 1960s prompted a revival of interest in evaluation. Recently, evaluators have not applied the major evaluation models to the evaluation of school systems, perhaps because the practice of internal evaluation focuses less on "program evaluation" than on operations research. The internal evaluator is an employee who holds primary responsibility for the organization's self evaluation. Information is provided to school staff in ways which are suitable to the administrators' decision-making styles. (GDC)