This article addresses three questions: why there was a surge in regional cooperation projects in Latin America in the last decade; how to characterize the current multi-faceted scenario; and how to make this complexity work. After a review of six theoretical perspectives, an original conceptual approach is proposed: "modular regionalism." This credibly answers the three questions and offers policy recommendations.

     As compared to other theoretical types designed to capture Latin American regionalism in the 21st century, modular regionalism combines a strong descriptive dimension with a plausible and pluralist explanatory dimension. It also formulates predictions for the future. Most of all, modular regionalism offers a prescriptive dimension, a set of policy propositions aimed to make regional complexity and overlapping work. 

     The new wave of Latin American regionalism in the 21st century is a wave of cooperation, not integration. This is why so many diverse projects can coexist. This is also why political discourse and the media talk integration while diplomacy and agreements on the ground concern in fact cooperation.