While many contemporary rural social movements once argued for increased industrial farming inputs and machinery for their members, the past few years have seen an accelerating shift toward the promotion of agroecology as an alternative to the so-called Green Revolution. In this paper we both describe this phenomenon in its historically specific context, and provide some theoretical tools for understanding it. From the construction of the food sovereignty paradigm by the transnational social movement La Via Campesina, which was critically shaped by the encounter and diálogo de saberes (dialog among different knowledges and ways of knowing) between different rural cultures (East, West, North and South; Peasant, Farmer and Rural Proletarian; etc.), and by the increasingly politicized confrontation with neoliberal reality and agribusiness in its most recent phase of expansion. We borrow the concepts of material and immaterial territories from Brazilian critical geography to understand both agroecologyas-practice and agroecology-as-farming in the growing territorial dispute between rural social movements and agribusiness, and the role played in these disputes by both as elements in the (re)construction of peasant territories. The paper provides examples of the construction of peasant territories and partial re-peasantization through agroecology, as part of the search by peasants for relative autonomy from input, credit and output markets around the world.