At large, research-intensive institutions graduate students are often funded as teaching assistants (TAs). Although the roles and responsibilities of TAs vary by locality and discipline, many are asked to deliver content and even serve as primary instructors. The use of TAs can be problematic given that many do not have backgrounds in pedagogy. Although TAs may possess the content knowledge, they may not have the pedagogical knowledge and pedagogical content knowledge required to teach undergraduate students. In order to increase the self-efficacy of TAs at a large, research-intensive university in the American Midwest, a series of teaching workshops designed and led by either faculty experts or the staff at the Teaching and Learning center has been developed. However, until recently, no efforts had been made to investigate the effectiveness of these workshops. This investigation recounts the results of self-reported evaluations by TA and non-teaching graduate student (NTGS) attendees intended to measure the degree to which TA self-efficacy related to the use of pedagogical knowledge and pedagogical content knowledge was impacted by the workshop series. Results indicate that all graduate students reported higher levels of confidence in their ability to implement pedagogical knowledge and pedagogical content knowledge after taking the workshops than they did on the pre-survey. There was a statistically insignificant trend for NTGS to report a larger change in self-efficacy. Recommendations for increasing TA self-efficacy and preparedness on university campuses are provided as are directions for future research.