The Trade Barrier Game is an experiential learning simulation for the IB classroom. The simulation is based on a multiparty, iterated, prisoner’s dilemma game, and has been adapted for IB classroom teaching. This pedagogical tool helps to make clear abstract concepts of political behavior in the world of trade negotiations. It enlivens the topic of the politics of trade. Students experience the behavioral and political dynamics of trade negotiations, and better understand how these dynamics can lead to a trade war. They come to see the benefits and challenges of cooperation within a competitive environment. Finally, the game is structured to show how cooperation between countries to reduce trade barriers, leading to freer trade, can generally produce gains for individual countries and the global economy. The simulation is suitable for undergraduate students in small and large class sizes, and can be played in a one-hour class session.