In recent years, neo-institutional sociologists, political scientists and geographers have engaged in a lively set of theoretical debates about how policy ideas move from one place to another. This paper seeks to engage with claims about global norm diffusion or policy transfer by studying policy discourses on agricultural development in the East African country of Tanzania. Using documents produced by international donors and research institutions, the Tanzanian government, and national and transnational civil society organizations; transcripts of parliamentary debates; and over 30 interviews with policy actors in Tanzania, we identify and compare three discourses that are currently circulating on African agricultural development policy: a global discourse, a dominant national discourse, and a subordinate national discourse. Based on an analysis of these discourses’ similarities and differences—and of the policy coalitions that are promoting them—we advance arguments about (a) the role of national contexts and historical legacies in shaping the diffusion of a global discourse; (b) power dynamics and political contention within the state itself; and (c) the transnational networks of both dominant and subordinate discourse coalitions.