We collected data from 149 graduate teaching assistants at a Midwestern university concerning their classroom duties, experiences with TA training and supervision, sense of self-efficacy toward teaching, preference for supervisory style, and feedback on those modes and skill domains in TA training they felt were most effective and best prepared them for academic careers. Results indicated that less than half of this sample of TAs received formal training for their duties and spent only approximately 40 clock hours in training. A majority of the sample indicated that they were receiving on-going supervision of their teaching duties. Findings also suggested that TA training and supervision are helpful in building TA self-efficacy toward teaching. With respect to supervisory style, TAs preferred a collegial style of interaction with their course supervisors. Finally, TAs found workshops or courses on college teaching as the preferred modality for their training, and most favored building skills in organizing their course materials, evaluating student learning, handling multicultural issues, and dealing with ethical issues in teaching. On the basis of our findings, we offer recommendations to university administrators regarding TA training. (Contains 4 tables.)