Calls for some form of world parliamentary body, most often conceived as a second `people’s’ chamber of the United Nations, have intensified in recent years. Such a chamber has been seen as an important potential corrective for a perceived global democratic deficit, as well as a means of promoting the interests of those excluded from global power centers. A social movement to create a United Nations Parliamentary Assembly has been endorsed by more than 600 parliamentarians from more than 90 countries. Yet, some view such movements as wasted effort, or worse, as effort that diverts needed energy and resources from alternate actions that could better promote just global outcomes. In this paper, I consider some pros and cons of promoting movement toward a UN Parliamentary Assembly, and world federalism more generally. The bulk of effort, I argue, should go to advocating the expansion of suprastate regional projects such as the European Union, and the strengthening and deepening of NAFTA, ECOWAS, ASEAN and similar projects. However, a rightly conceived UN Parliamentary Assembly could play an important complementary role in helping to protect individual rights, and in securing more just outcomes more generally in the global system. Its development, while not the most pressing item on the global justice/global citizenship agenda, should not be discouraged.