The purposes of this study were to determine changes in teaching efficacy of student teachers over the course of the student teaching semester and to determine if similar trends occur at different institutions. The population of interest for this study was agricultural science student teachers at Tarleton State University, Texas A&M University, Texas Tech University, and Oklahoma State University. The accessible sample of the population was student teachers during the Spring 2005 at Tarleton, Texas A&M, and Texas Tech Universities and the Fall 2005 semester at Texas A&M and Oklahoma State Universities (n = 99). Using the Teachers' Sense of Efficacy Scale instrument (Tschannen-Moran & Woolfolk Hoy, 2001), efficacy in student engagement, efficacy in instructional strategies, and efficacy in classroom management, and overall teaching efficacy were measured: 1) the first day of the 4-week on-campus portion of the student teaching semester; 2) the last day of the 4-week on-campus block; 3) the middle of the 11-week student teaching experience; and 4) the final day of the student teaching experience. It was concluded that overall teaching efficacy changed. Student teachers had "Quite a Bit" of teaching efficacy at the beginning of the semester, which increased slightly 4-weeks later, then decreased to its lowest level at the middle of the 11-week student teaching experience, and then increased to its highest levels at the end of the experience. (Contains 6 tables and 4 figures.)