The employment of graduate students on a part-time basis to help with the teaching of undergraduates is growing in the UK and many higher education institutions are confronted with challenges about how best to do this. UK institutions have much to learn from North American experience of appointing graduate teaching assistants (GTAs), and this paper seeks to highlight key lessons by reviewing published literature on the use of GTAs in North America. After sketching out the emerging context in the UK, some important implications of North American experience in the selection and preparation, training, supervision and mentoring of GTAs are explored. The paper also identifies lessons relating to practical issues (including communication and managing conflict), personal issues (including reflective practices, and issues of identity and self-worth) and professional development issues (including GTAs as aspiring academics and the ambiguity of the GTA role).