This chapter presents, at length, a theoretical argument linking economy geography, federal institutions, and patterns of party competition to explain how agricultural interests’ institutionalized political resources—or their absence—shape policy outcomes. Grounding the theory to the cases, the chapter shows how the territorial footprint of soy production, together with federal malapportionment and electoral and campaign-finance rules, conditioned how agricultural interests' economic weight translated into institutionalized representation. In Brazil, production spread across multiple states; open-list proportional representation and lax campaing finance rules fostered autonomous rural representation; and partisan fragmentation in a robust federation multiplied access points, calling for oversized presidential coalitions that made accommodation the path of least resistance. In Argentina, production was concentrated in core provinces; closed-list PR, centralized party control of candidate selection, and public campaign finance limited independent sectoral representation, easing executive moves toward export taxation and amplifying distributive conflict. These alternative patterns of accumulation of political resources by agricultural interests in turn explain that under similarly left governents and price boom Argentina moved toward heavy rent appropriation from export agriculture while Brazil pursued a more accommodative course.