The improvement of teacher performance requires the accurate identification of a teacher's strengths and weaknesses. However, effective teachers, in addition to utilizing certain effective teaching skills, are strengthened by certain affective skills which are difficult to identify and, consequently, to measure. The research has identified a whole host of teacher behaviors that are clearly related to student achievement. This study, in addition to assessing those observable teacher behaviors, sought to particularize their personality characteristics and measured their feelings of self-efficacy, which refers to the extent which teachers believe that they have the capacity to affect student performance;Seventy classes, thus teachers, were involved. A change score report for the entire year in both criterion-referenced and norm-referenced tests (pretests in September and posttests in May) was created subsequent to each spring testing. Those teachers whose average change score was greater than that of his/her school organization's average change score were classified as high-gain teachers. In addition, the teachers in the project were evaluated utilizing a research-based performance evaluation instrument. Thus, both reports of individual teacher evaluations and the achievement measures of their students were available;Teachers and their supervisors were asked to complete the SIM Teacher Performance Evaluation Instrument and a comparison of ratings was conducted. To determine the personal characteristics of the high-gain teachers, the Personal Profile System was used. Finally, to assess the feelings of self-efficacy, the Responsibility for Student Achievement Questionnaire was utilized;Findings. (1) High-gain teachers rated themselves significantly higher than their supervisors rated them on 18 out of 25 effective teaching criteria. (2) High-gain teachers exhibited characteristics in all four of the dimensions of behavior assessed by the Personal Profile System: 42% exhibited an "influencing of others" style of behavior, 29% "compliance," 19% "steadiness," and 10% "dominance." (3) High-gain teachers have a strong belief that they have control of factors that influence students' successes and failures in the classroom. (4) There was no significant difference between male and female high-gain teachers in feelings of self-efficacy.