Abstract: Two theories dominate the current debate on group agency: functionalism, as endorsed by Bryce Huebner and Brian Epstein, and interpretivism, as defended by Deborah Tollefsen, and Christian List and Philip Pettit. In this paper, I will give a new argument to favour functionalism over interpretivism. I discuss a class of cases which the former, but not the latter, can accommodate. Two features characterise this class: First, distinct groups coincide, that is numerically distinct groups share all their members at all time. Second, we have access to the inner mechanisms of the groups agents, because members know what they have decided on. I construct a counterexample with these features allowing me to reject interpretivism about group agency in favour of functionalism.