How should a political society be structured so as to legitimately distribute political power? One principle advanced to answer this question is the principle of subsidiarity. According to this principle, the default locus of political power is with the lowest competent political unit. This article argues that subsidiarity is a structural principle of a conception of political legitimacy informed by epistemic considerations. Broadly, the argument is that political societies organised according to the principle of subsidiarity can more effectively achieve political decisions that can justifiably appear to be correct from the point of view of those subject to them. The article presents two considerations in order to establish a pro tanto case for acting separately before presenting five additional epistemic considerations that establish a prima facie case for acting separately. The article then shows that political legitimacy and the epistemic aim of decision‐making can sometimes be served more effectively and efficiently by allowing higher‐level political units to assist lower‐level political units.