Teacher educators continually strive to find ways to improve the preparation of preservice teacher candidates. In the area of mathematics education, methods courses that follow National Council of Teachers of Mathematics (NCTM) standards for professional development have been successful. This study supports the notion that a mathematics methods course can improve mathematics teaching efficacy in the constructs of personal mathematics teaching efficacy (PMTE) and mathematics teaching outcome expectancy (MTOE). Findings also suggest that mathematics teaching efficacy is developmental in its nature with PMTE developing before MTOE. Employing a quasiexperimental nonequivalent comparison groups pre- and posttest design, the present study examined the effects of guided imagery as an added component of a mathematics methods course and found no significant advantageous treatment effects on mathematics teaching efficacy. However, there were no detrimental effects on mathematics content knowledge and pedagogical skills either. Participation in a reform-based mathematics methods course did affect mathematics teaching efficacy for both groups in the study. Mathematics teaching efficacy beliefs were measured by the Mathematics Teaching Efficacy Beliefs Instrument (MTEBI), and data were analyzed by ANCOVA and paired-samples t-tests. Recommendations for further research on the developmental nature of general teacher efficacy and mathematics teaching efficacy are included.