We report a small-scale research project in which an English and a French student teacher work collaboratively to develop their personal knowledge and understanding of grammar and its role in teaching both subjects to 11-year-old learners in an English comprehensive school. The project begins with university-based discussions about the role of grammar in language learning as expressed in a number of government documents and professional journals. It then continues in school where the students observed lessons given by experienced teachers and by each other. Ways in which the cross-language focus beneficially influenced their classroom practice are suggested. The article discusses a number of issues arising from the project about planning for language development and teaching about language across the curriculum and we make some modest proposals for a way forward within government policy, which remains separatist.