At the end of the Mexican-American War in 1848, the United States annexed what had been the Mexican Department of New Mexico, and as it did, it absorbed millions of acres of agro-pastoral land whose parcels had been under a communal system of ownership by Mexican citizen-villagers. From the heirs’ point of view, the subsequent American system of adjudicating ownership of these traditional properties proved inadequate, leading to the loss of two-thirds of their commons to American land speculators and the U. S. National Forest. Like the Native Americans, the heirs of these grants have long seethed in resentment over the steady erosion of their hold on their traditional lands and culture. This article outlines the processes of despoliation of the land grants from their original owners, and, more centrally, suggests the historical cycles of collective struggle that the heirs have mounted since the 1840s in order to retain and wrest back their commons, as well as organize the grants that they have been able to secure. A stubborn land-grant movement has gone through various forms of collective action including clandestine violence, protest confrontation, legal strategies, and political lobbying. In the most recent phase, activists have hopeful signs that the U.S. Congress is ready to respond to their demand for return of commons now under federal jurisdiction.