What big questions and large-scale narratives give coherence to the history of science? From the late 1970s onward, the field has been transformed through a stress on practice and fresh perspectives from gender studies, the sociology of knowledge, and work on a greatly expanded range of practitioners and cultures. Yet these developments, although long overdue and clearly beneficial, have been accompanied by fragmentation and loss of direction. This essay suggests that the narrative frameworks used by historians of science need to come to terms with diversity by understanding science as a form of communication. The centrality of processes of movement, translation, and transmission is already emerging in studies of topics ranging from ethnographic encounters to the history of reading. Not only does this approach offer opportunities for crossing boundaries of nation, period, and discipline that are all too easily taken for granted; it also has the potential for creating a more effective dialogue with other historians and the wider public.