This research is an interpretive study of individual and institutional language practices based on an analysis of quantitative and qualitative data from a large higher education institute of teacher training in Britain. The study explores teacher professionalism in relation to language, examining the "invisible" linguistic and cultural capital of multilingual student teachers. This capital is a potentially powerful contribution to student teacher pedagogy and professionalism, but in the two key domains of teacher education (university and school) where practitioner "funds of knowledge" are manifested in events and activities, the study reveals how multilingual students struggle to create or access events and activities where they can demonstrate and develop their "knowledge in action". The discussion frames multilingual student teachers and multilingual pupils as mirror participants in monolingual institutions and explores issues of subordination, investment and empowerment in relation to language use. The study presents multilingual student teachers as multi-competent language users who could positively influence wider pedagogic knowledge and practices but who are prevented from activating their linguistic, cultural and community expertise through institutional and professional lack of recognition. (Contains 1 table, 1 figure, and 6 notes.)