This article compares variants of republican and liberal theory in order to assess which can make a stronger proprietary claim to the new democratic practice of citizens' assemblies (CAs). I argue that in respect of the categories of representation, liberty and citizenship, CAs are primarily republican in character. The argument is significant for three reasons. First, the political theory terrain is remapped, affirming clear differences between liberal and republican theories while maintaining an appreciation of what they share. Second, a complex intertwining of negative, positive and republican forms of liberty emerges, which runs contrary to an established tendency where modes of liberty are conceived according to excessively narrow parameters. Finally, supporters of the republican revival in political theory acknowledge that its future success depends on real institutional innovations. Yet this challenge has been taken on ‘timidly and inadequately’ in the judgement of one prominent republican. This article presents the CA model as an ideal existing institution worthy of full republican support.