This paper investigates the role of interpreters in addressing cultural differences in the context of a cross-cultural collaborative teacher professional development project. Based on positioning theory, this study employed interpreter-mediated interactions and interviews to reveal the complex roles that interpreters played when interpreting culture-related terms. Findings revealed that interpreters' roles were shifting between those of transmitters of information, cultural insiders and constructors of shared understandings between interlocutors. Notably, the lack of training in this specialised field obliged interpreters to rely mainly on their personal experiences to judge which role they should play in the face of cultural differences.