Two methods (generic or specific) of assessing competency based teacher performance were compared in three studies with 158 special and regular teachers. Two classroom observation instruments - one designed to measure generic teaching competencies at all levels and across all subjects, the other developed for special education teachers only - were evaluated. Study 1 was to determine which competencies from either instrument can successfully discriminate among special education teachers according to an external criteria measure. Study 2 used a different measure to test the validity of the instruments and examined minimal competency ratings. Study 3 attempted to discover how special and non-special teachers differ in competency as a content validation procedure. It was concluded from the studies that generic teaching competencies do exist and can be measured but that special education teachers require additional specific assessment items. Appended are "The Beginning Teacher Assessment Instrument", "The Classroom Observation Scale", and data tables. (Author/PHR)