This report discusses the findings of a study that examined the reflections of identified "expert" special educators (n=20) working in a variety of instructional settings with diverse student populations. Special education supervisors were asked to nominate teachers who: (1) had at least five years of teaching experience, (2) were recognized among their peers, parents or the community as being effective teachers, (3) instructed students that generally made excellent progress in achieving their individualized education plan objectives, and (4) were viewed as superior special education teachers. Teachers viewed videotapes of themselves teaching and recalled thoughts or feelings that occurring during the instruction. Results indicate that teachers made frequent use of "instructional diagnosis," in which teachers used extensive content knowledge and the particular knowledge of the student to arrive at a diagnosis. Immediately following the diagnosis, they applied a modification to remedy the learning difficulty that the student was encountering. This procedure was repeated numerous times over the course of the instructional period, with a diagnosis of one student often being made several times in the space of five or ten minutes. This instructional diagnosis did not seem to rely on the category assigned to a student; instead, teachers closely observed the progress of the student, basing their observation on the student's progress, together with their past knowledge of the student. (Contains 35 references.) (CR)