Despite curriculum reforms emphasizing intercultural competence in Korea and Taiwan, EFL teachers face persistent gaps between intercultural ideals and institutional realities, including assessment pressures, time limitations, and resource scarcity. Traditional oneshot professional development rarely addresses these tensions, leaving teachers unsupported in implementation — a gap this dyad-level case is positioned to trace in situ.
This study examines one teacher dyad in a 16-week transnational university-school partnership, both of whom wanted to teach interculturally but felt limited by their institutional contexts. Drawing on third-generation Cultural Historical Activity Theory, this paper shows how the partnership functioned as a critical third space — mediating between activity systems through intellectual legitimation, responsive mediation, crossborder solidarity, and research-practice bridging — to enable strategic integration despite ongoing pressures. Both teachers demonstrated strategic integration of intercultural teaching into required curriculum, with one independently designing a follow-up lesson and the other incorporating project materials into formal assessment within two weeks of the program’s conclusion. Findings suggest how partnership design can support intercultural teacher development in constrained contexts, offering a transferable model for Asia-Pacific reform implementation.