Export-oriented development strategies and trade regimes encourage the incorporation of developing country exports into northern markets, often bringing them into competition with domestic suppliers. While studies of transnational commodity flows focus on the organization and coordination of economic activities over geographic space, little research has been done on their competitive relations. In this article, I focus on the political economy of disputes over market access by linking trade regimes to the economic and political activities of actors in the rival Colombian and US cut flower commodity chains. I argue that the regulation of the Colombian and US cut flower commodity chains is a process marked by institutional mediation and political and economic contestation. In shaping their economic spaces, a combination of shifting discourses, litigation, and political lobbying in sites of power are used by economic actors to meet their interests. The examination of rivalry over market access shows variation in the configuration of economic activity in the US cut flower market over time while drawing attention to the dynamic interaction among economic actors, institutions, and markets.