Contrary to conventional wisdom, this article argues that trade liberalization may facilitate collusion and reduce welfare. With the help of a duopoly model in which firms interact repeatedly in multiple markets, we first show that, if trade costs (i.e., tariffs/transport costs) and discount factors are not too high, efficient cartel agreements necessitate the cross-hauling of goods, as that entails lower deviation incentives. In this setting, we then demonstrate that reciprocal trade liberalization always raises total output when trade costs are within a range whose lower bound exceeds a threshold level, but may reduce total output (and thus be pro-collusive) when trade costs are below that threshold level.