When scientists talk about science in public they are not just disseminating knowledge. They are also representing science and its organizations in a very broad sense and enacting particular understandings of what science, scientific organizations and scientists are and should be. Using examples from the field of synthetic biology, this paper reflects upon the ways in which science communication shapes identities, whether those of nations (for instance through the ways in which science is viewed as fundamental for the creation of innovative, knowledge-driven societies), organisations (such as universities or disciplines), or individuals (whether scientists, patients or other 'users', or citizens). Borrowing from theories of organizational communication, the relationship between communication, identity and culture is brought to the fore of our attention. It is demonstrated how science communication is crucial for professional and organizational identity, and how it is part of the making of science through the generation of expectations and resources.