Abstract The rise of nationalist and populist movements throughout the world has led to concerns about the future of the liberal international economic order. Central to these worries is the belief that nationalist and populist publics and their leaders will reject open trade, which has been a cornerstone of the global order. Yet despite these fears, very little empirical research has been conducted on the links between either nationalism or populism and trade policy. In this paper, we argue that nationalism and populism are likely to discourage trade liberalization in democratic states, but that these forces will have little influence on trade policy in non-democracies. To test this argument, we focus on state involvement in preferential trade agreements (PTAs). Based on a variety of tests, we find considerable support for our argument. Democracies with nationalist or populist governments are especially reluctant to join PTAs, but neither nationalism nor populism systematically influences whether non-democracies enter PTAs.