This article reports on a study with over 100 Graduate Teaching Assistants (GTAs), 69 of whom were international GTAs. We explore their experiences of 'cultural bumps' in their transition into one UK University. Following the principles of practice-based enquiry, data collection combined interviews with data generated in workshops, including transcripts, fieldnotes, student feedback and LEGO® models. We focus on three themes of starting teaching, essay marking and classroom boundaries to explore 'cultural bumps' where GTAs experience adjustment stresses transitioning into UK higher education teaching. We connect 'cultural bumps' to challenges reconciling teaching and researcher roles for GTAs. We conclude with an agenda for research work to further develop our understanding of international GTAs' experiences.