This study sought to determine discriminating, reliable, and valid criteria to evaluate the performance of special education teachers. Data were collected on criteria to distinguish high performing special education teachers from average and poor performing special education teachers. A sample of over 500 principals/supervisors, teachers, related services personnel, and knowledgeable others was administered a 49-item questionnaire. In addition, the investigation endeavored to determine if appraisers' ability to rate a special education teacher varied according to job assignment. In particular, it tried to verify the ability of typical building principals to make performance evaluation judgments about special education teachers. The study also attempted to determine whether a difference existed between discriminating items for regular and special education teachers. Voluntary participation for the study included 33 special education teachers from school districts located in Arizona, Arkansas, Iowa, Montana, New York, and Nevada. Each of the 33 special education teachers was evaluated by 15 to 18 raters;Results showed that: (1) all 49 of the survey items discriminated or measured differences between the 33 special education teachers at least at the.05 level of significance; (2) performance criteria found to be discriminating for regular education teachers were also able to discriminate for special education teachers; (3) ratings by raters with little or no special education background were not significantly different from raters with certification in special education; (4) effective teacher behaviors in the regular classroom appear to be effective behaviors for the special education teacher; (5) effective behaviors of special education teachers appear to be readily observable by a variety of observers with various backgrounds and training; and (6) regular educators, particularly principals and supervisors, are capable of making valid observations of special education teacher performance;The study also includes a list of 49 performance criteria for special education teachers based on discrimination power that may be used to develop a performance evaluation instrument for special education teachers.