This study aims to elucidate (1) the setbacks graduate students face as Graduate Teaching Assistants (GTAs), (2) the mechanisms through which overcoming these setbacks is possible, and (3) the meaning of the GTA experience, particularly for graduate students specializing in subject education. To answer these questions, we consider Chris Park’s article “The Graduate Teaching Assistant (GTA): Lessons from North American Experience.” This study was introduced by Sherry Field when she took the podium at the RIDLS lecture meeting as a beneficial reference that provides an overview of North American trends in GTA research. Indeed, it is a comprehensive review that has been quoted and consulted by many previous studies. Thus, for this study we decided to approach the above questions by reviewing Park’s article. The following three points became clear from this analysis. First, as GTAs, graduate students tend to suffer setbacks in terms of constructing relationships with others, allocating time between research and education, inadequate knowledge and experience, and demonstrating an open attitude toward diverse ideas that differ from their own. Second, it is none other than the GTA system itself that can overcome difficulties GTAs face. A GTA program for this purpose must offer opportunities for legitimate peripheral participation in a community of researchers and educators. Furthermore, there is need for coherent selection and preparation, training, and supervision and mentoring mechanisms. Third, the GTA experience is an opportunity for heightening not only capacities and abilities as educators (teacher trainers), but capacities as researchers and educators (teachers in training). For graduate students specializing in subject education (one in which the methodologies of educators and researchers are closely connected), learning as a GTA can be expected to be effective.