This paper articulates a functionalist account of intra-party democracy (IPD). Like realist critics, we insist that IPD practices be evaluated on the basis of whether they facilitate resistance to domination and capture at the level of the polity as a whole, and therefore accept certain realist worries about IPD. Yet realists neglect the possibility that wealthy interests could control the political agenda by capturing all viable parties simultaneously-and that mass-facing IPD could counter this threat of oligarchic agenda capture. Taking this as the key function of IPD within broader democratic systems, we conclude that inclusionary party reform is less urgent in more flexible party systems, where dissenters are better able to resist this threat from within the framework of inter-party competition. Regardless of the context, meanwhile, we also conclude that mass-facing IPD practices should aim at enabling ordinary members and supporters of a party to resist agenda capture by oligarchic interests. Though we stop short of defending any particular set of reforms, we reject the emphasis of recent IPD advocates on individualized forms of deliberative participation, in favor of a more oppositional and collectively-oriented approach-on the grounds that the latter is more likely to encourage the development of effective institutions of countervailing power.