This study investigated changes in teaching efficacy during student teaching using a modified version of the Teacher Efficacy Scale. The study occurred over three-quarters of one academic year, with the survey instrument administered to all student teachers at one small, private college during student teaching orientation. Students were placed in a variety of student teaching settings, mainly in suburban schools. During the final 2 weeks of student teaching, all preservice teachers completed the instrument again. A total of 100 usable forms were obtained over the three quarters. Data analysis indicated that the group as a whole showed a statistically significant gain in efficacy as a result of student teaching, though there were differences between elementary and secondary preservice teachers. There were no statistically significant changes by gender in scores between pretest and posttest. The results suggest that preservice teachers' efficacy prior to student teaching is a reasonable predictor of efficacy after student teaching ends. The survey is appended. (Contains 10 references.) (SM)