This chapter reflects on the questions of what is involved and what is at stake in teaching for Global Citizenship within national curriculum frameworks in the transnational and transcultural space of classrooms with diverse students. In an attempt to move beyond predefined criteria of teachers’ competencies, the author explores the lived experience of teaching in culturally, ethnically, nationally and linguistically heterogeneous classrooms characterised by transnational migration, in terms of practical wisdom, moral judgment and pedagogical tact. Drawing on interview data from teachers’ day-to-day experience the author argues that there is more to pedagogic competence than teachers’ knowledge of and commitment to diversity and social justice. The language of phronesis and tact complicates and complements the language of teacher efficacy and proves to be helpful in learning to teach in these spaces of collision, tension and possibility.