The urgency of improving teaching and learning in undergraduate mathematics education is deepening and graduate teaching assistants (GTAs) are becoming increasingly responsible for taking on this task. However, differences in GTAs training, GTAs actual teaching experience, and the goals and aspirations these students set for themselves, makes it difficult to assess the GTAs efficacy and ultimately their effectiveness in the undergraduate classroom. Using Denham and Michael (1981) Teacher Sense of Efficacy Model as a framework, the aims of this study were (a) to examine the impact pedagogical preparation, teaching experience and future career plans (FCP) have on teacher efficacy (TE) and (b) to determine whether pedagogical preparation, teaching experience and FCP together are significant predictors of TE. This correlational study used an ex post facto design in order to evaluate variables such as pedagogical preparation, teaching experience, and future career plans. Data was collected regarding the demographics and teaching beliefs of each voluntary GTA from the participating mathematics departments classified by Carnegie as research universities-extensive. In this correlational study, Pearson’s Product Moment Correlation (Pearson’s correlation) was used to examine the relationship between pedagogical preparation, teaching experience and future career plans with TE. A test of multiple regressions was also conducted to determine the significant predictors of teacher efficacy. Positive relationships were found between pedagogical preparation, k-12 teaching experience, future career plans and TE. K-12 teaching experience and future career plans were also found to be significant predictors of TE.