Undergraduate and graduate teaching assistants (TAs) play large roles in introductory undergraduate education despite having little to no teaching experience or professional development (PD). Self-efficacy and teaching approach have each been studied as independent variables that impact teaching performance and student learning in the absence of practiced skill or developed knowledge. This study explored relationships between TAs' teaching approaches and teaching self-efficacy. Self-efficacy was measured using the Graduate Teaching Self-Efficacy Scale (GTA-TSES), and teaching approach was measured using the Approaches to Teaching Inventory (ATI). The following research questions guided the study: What is the relationship between TAs' approaches to teaching and their self-efficacy? How do approaches to teaching and self-efficacy interact to impact the model of TA self-efficacy? Both ATI subscales correlated strongly with the GTA-TSES learning environment subscale and weakly with the instructional strategy subscale. High self-efficacy TAs demonstrated more concern with impacting student learning, which may contribute to a more student-centered teaching approach. Results indicate that TAs with more confidence in their teaching ability may have a more student-centered approach than teacher-centered approach to teaching. Implications include enhancing TA PD with peer mentoring, constructive feedback, and reflection and incorporating learning concerns in the model of TA teacher efficacy.