In the mid-twentieth century, Mexico became a hub for global experiments in public health and social science. Best known as the birthplace of the Green Revolution, Mexico also pioneered the first large-scale effort to train community health workers to combine Western medical practices with Indigenous healing traditions. The Power to Harm and Heal uncovers how that groundbreaking program, led by the state-run Instituto Nacional Indigenista, reshaped healthcare across rural Mexico. Drawing on archival sources and oral histories, Joshua Mentanko illuminates the lives and labors of the early intercultural health workers who toiled in this program decades before international health agencies adopted similar models. Mentanko also examines the complex relationships between policymakers, scientists, and the communities they aimed to serve, and how medicine became a tool for both nation-building and cultural negotiation. Further connecting Mexico's rural health initiatives to shifting global geopolitics, Mentanko elucidates how such initiatives emerged alongside decolonization movements and Third World struggles for economic development. Placing intercultural medicine at the center of debates surrounding modernization, Indigenous rights, and the global history of primary care, The Power to Harm and Heal reveals the critical roles Indigenous people-as western and traditional medicine practitioners and patients-played in the creation, development, and resistance to the shifting practice of medicine.