How should the geographic boundaries of democratic participation be set? This has been a notoriously difficult theoretical question, beset by paradoxes around determining democratic participants democratically. It also is seen as increasingly important in practical terms, amid deepening interdependence between states, immigration tensions, and suprastate regional integration. Numerous recent accounts have called for extending participation beyond the state. The case is generally made on intrinsic grounds: democracy demands it. Respect for individual autonomy is said to be violated when outsiders are deeply affected by decision processes, or subject to coercion from them, without being able to participate in them. Yet, familiar problems around restrictions on the autonomy of persistent democratic minorities remain in such accounts, and they could be magnified with expanded boundaries. An alternative approach is offered here, grounded in a rights-based instrumental justification for democracy. It sees participation as foundationally – though not solely – valuable as a means of promoting and protecting fundamental rights. It recommends extending participation boundaries to reinforce protections within regional and ultimately global institutions. Democratic participation would remain crucial at all levels, not principally as an expression of autonomy but to provide checks on power and promote accountability to individuals in multilevel polities.