Summary: The authors offer a theoretical contribution to the discussion of transfer from a situated point of view. They reconceptualise what, within the school context, might be thought of in Bernstein\rq s terms as the transfer of knowledge between two insulated vertical discourses. They describe an interdisciplinary project carried out by secondary mathematics and science teachers, and present two accounts of learning episodes to illustrate and amplify their ideas. They conclude with some discussion of how they might plan to develop interdisciplinary work using ideas of community of practice.