Discussion sections in large-enrolment undergraduate psychology courses can foster the development of teaching assistants (TAs) as instructors while also promoting student learning. This research note discusses specific strategies for accomplishing this, including the balance of structure and flexibility in supporting novice instructors, peer mentoring within a lead-TA model, integrating assistantships with instruction on the scholarship of teaching, and recognising the power of labels in shaping student and TA perceptions of the discussion section.