Building on Trust examines how a handful of progressive Christians from Americus, Georgia, expanded a local organization into the world's largest housing nonprofit. Habitat for Humanity followed the insights of antisegregationist minister Clarence Jordan, realized by its founder, Millard Fuller, and amplified by Jimmy Carter, its volunteer-in-chief. In 1979 Fuller opened the first Latin American affiliate in Guatemala. Today Habitat Guatemala is an entirely self-financed, Guatemalan-led organization that has built more than seventy-five thousand houses over four decades. Its success rested on a common faith and mutual reliance among U.S., Ladino (non-indigenous Guatemalan), and Maya agents and the communities where they worked. These trust bonds, however, were repeatedly tested and reshaped by tensions between the international headquarters, which introduced neoliberal management practices in the 2000s, and the Maya grassroots actors, who sought to preserve Habitat's humanist Christian tradition. Despite these challenges, the story of Habitat Guatemala stands in contrast to the typical failures in international development projects. It demonstrates how a foreign aid organization became locally embedded, negotiating the unstable balance between global power structures and local demands. At a time when international relations are increasingly based on the use of force, this example of society-to-society collaboration warrants a second look.