Although the main activity of postgraduate students is research, many also have significant teaching roles and responsibilities. These individuals are known as graduate teaching assistants (GTAs). Their role is particularly significant in research-intensive institutions (Travers, 1989). For example, one recent estimate reported that 85 percent of the undergraduate courses within a school at a research-intensive Canadian university were taught by non-faculty staff, many of whom were postgraduates (Hickson and Fishburne, 2007). GTAs support undergraduate student learning in various different teaching contexts, and their roles vary in relation to disciplinary contexts, opportunities and constraints. Typical responsibilities of GTAs include facilitating student learning and helping students prepare for assessments (Morss and Murray, 2005). In some higher education institutions, particularly in the United States, the role of GTAs is officially recognised with employee status, whereas in others the role is not as formalised (Park, 2004). Even within an institution, support and recognition may vary from department to department. Postgraduates’ motivations for becoming involved in teaching vary considerably, and may include the need to supplement their incomes as well as a desire to gain experience in teaching as preparation for developing their career prospects (Park, 2004; National Postgraduate Committee, 1993).