Graduate teaching assistants (TAs) are often responsible for teaching introductory courses to undergraduate science, technology, engineering, and mathematics students. The TAs are usually novices at teaching, and an important factor in their resilience and persistence in the face of inevitable challenges is self-efficacy. Little is known about what affects TA teacher efficacy or whether and how high- and low-efficacy TAs differ in their develop­ment as teachers. Bridging these gaps in the literature will inform best practices in devel­oping and implementing professional development (PD) for TAs. Using a mixed-methods sequential exploratory research design, this study found differences in high- and low-ef­ficacy TAs in both TAs’ self-reflection and their students’ perceptions. These differences concerned the focus of TAs’ attention: Inward at their own practices and emotions (salient in low-efficacy TAs) versus outward at the impact of their instructional guidance on their learners (prevalent in high-efficacy TAs). A proposed model of teacher efficacy based on TAs but generally applicable is presented to inform future research and provide sugges­tions for TA PD opportunities.

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© 2021 The authors. This article is distributed by The American Society for Cell Biology under license from the authors. It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

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CBE Life Sciences Education