This chapter builds on analyses of environmental mobilizations that have focused on the plurality of networks between organizations. This approach has only been applied to select aspects of the Mexican movement. Unlike a somewhat idealized analysis of social movements focused solely on grassroots mobilizations, an approach focused on coalitions can show that the different actors mobilized are connected to one another as much by complementarity and division of labor, as by a shared set of common values. Environmentalism is often characterized by a “transclassist” heterogeneity of participants, and coalition building is therefore the most common way to expand a mobilization. This is the distinct nexus between “elitist” and “grassroots” organizations, as well as the two distinct historical trajectories of alliances that allow us to empirically divide what we might call “Mexican social environmentalism” into two components.