In the Parque de la Papa (Potato Park), in the Peruvian Andes, communities of farmers conserve native potatoes, work that holds promise for global food security but is made precarious by mounting pressures from climate change and a market-based economy. Using a community-level analysis of ethnographic research, I argue that a moral economy undergirds the social structures in the Parque, framing relationships within communities and potato fields and with agents beyond: the closely linked NGO ANDES, the state, international partners, corporations, and potatoes. Ethical relationships are organized by Andean values, within ecological–social–political communities called ayllus and through farmers’ commitment to ayni [reciprocity]. This moral economy breaks down at multiple levels. Certain breakdowns are longstanding, as in the Peruvian state’s prioritization of mining concessions over campesino land rights. Yet climate change causes increased strain, leading some farmers to integrate in the capitalist economy and absent themselves from the moral economy. There are also positive interventions to these harms. Most notably, through ANDES and the Potato Park project, as well as the municipality of Písac, communities create bulwarks defending themselves from the state’s and climate change’s affronts to Andean values—and the local values in prospective Parks around the world.