This paper is a review of the methodological problems recently uncovered in studying the nature of teacher effectiveness and evaluating the performance of individual teachers. Four problems encountered in the literature are range of measurements, inconsistent instrumentation across similar studies, lack of a generic framework from which to select behaviors to be measured, and use of instruments with inadequate psychometric characteristics. These problems are discussed. From a review of the literature, three general dimensions were selected from the purpose of categorizing classroom behavior and the instruments used to measure it. These dimensions were: (1) stage of behavior on a process-product continuum; (2) level of inference required in measuring behavior, and (3) objectives of the instruction. If the measurement of behavior is viewed as a longitudinal process, four distinct and consecutive measurement stages are apparent: (1)Preoperational (personality, attitude, experience, and aptitude/achievement); (2) Immediate (sign, counting, and rating systems); (3) Intermediate (Likert and Guttman Scales, semantic differentials and check lists); (4) Product (influences other than the teacher, unreliability of the raw gain score, and the teacher's desire to teach to the test). Last, some guidelines are offered for improving the measurement process. (RC)