Stephen Butterfill gives a talk on philosophy and collective agency and other people's minds When friends walk together, they typically exercise collective agency. By contrast, two strangers walking side by side exercise parallel but merely individual agency. This and other contrasts invite the question, What distinguishes collective agency from parallel but merely individual agency? To answer this question, philosophers standardly appeal to a special kind of intention or structure of intention, knowledge or commitment often called ‘collective intention’. The idea is that exercises of collective agency stand to collective intention much as exercises of ordinary, individual agency stand to ordinary, individual intention. In this talk I shall use this parallel between individual and collective intention to argue that some forms of collective agency are grounded in representations and processes more primitive than those associated with collective intention. Collective agency is not always a matter of what we intend: sometimes it constitutively involves certain structures of motor representation. One consequence is concerns a role for collective agency in explaining knowledge of others’ minds. Reflection on what is involved in sharing a smile suggests that there is a route to knowledge of others’ mental states that is neither straightforwardly perceptual nor inferential but hinges on interaction Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales; http://creativecommons.org/licenses/by-nc-sa/2.0/uk/