Case studies of two students with pervasive developmental delays illustrate the conflict between belief-based versus measurement-based approaches to planning educational services for students with diverse abilities. The doctrinaire view embraces inclusion as an end in itself. Placing students with diverse abilities, even severely handicapping conditions, in regular classrooms is itself the goal. Teacher preparation, social acceptance by peers, and classroom modifications are details to be worked out later. The rational inclusion view sees inclusion as an ongoing process. The preparation of the teacher, classmates, and other classroom variables are seen as necessary prerequisites to the eventual placement of the student in the regular classroom. Individual students with similar diagnoses may require different educational services, each of which may be consistent with inclusion for that student. These options should be evaluated on their merits. Team members preparing IEPs often choose a path on the basis of personal preference as if it were an immutable decision. When the discussion is couched in terms of "right or wrong" rather than in a problem-solving mode, it is difficult to formulate compromise options such as trial periods and measured progress. Teachers who are problem-solving oriented; team leaders who are independent and skilled; parents with access to training and information; and the use of more rational, versus doctrinaire, approaches will result in more successful school inclusion. (TD)