Our global food system is largely based on unsustainable industrial agricultural practices, is a major source of greenhouse gas emissions, is controlled by a handful of large corporations and produces unhealthy food. Agroecology is a solution to these increasingly urgent problems. After decades of being dismissed by mainstream institutions and defended in obscurity by grassroots movements, some scientists and farmers, agroecology is suddenly in fashion. The United Nations Food and Agriculture Organization, government agencies and even corporations are jumping on the bandwagon. But, are they for the same agroecology as developed by pioneering farmers, scientists and peasant social movements, or are they seeking to co-opt the concept and give it different content? Rosset and Altieri, two of the world's leading agroecologists, outline the principles, history and currents of agroecological thought, the scientific evidence for agroecology, how to bring agroecology to scale and the contemporary politics of agroecology.