The production and consumption of quinoa (Chenopodium quinoa Willd.) have grown rapidly in recent years, spreading far beyond its traditional growing region of the Andes Mountains in South America. The increase in consumption is due primarily to its high nutritional value and flavorful seed, whereas the expansion in production area is due to the broad adaptability of the species across a wide range of latitudes, altitudes, precipitation zones, soil types, and salinity levels. Efforts are underway across the globe to develop regionally resilient quinoa cultivars and productive cropping systems. The recent publication of the quinoa genome has opened avenues of research previously unavailable in quinoa breeding and should contribute substantially to the development of improved cultivars. This chapter reviews the evolution of quinoa and its wild relatives, the traditional ecotypes from which the majority of modern cultivars descend, and the history of quinoa breeding in South America. It discusses quinoa’s reproductive and pollination systems, as well as recent advances in the genetics and genomics of this allotetraploid species. Following an overview of quinoa breeding methods, it focuses on breeding objectives, including yield potential, traits of agronomic importance, tolerance to abiotic and biotic stresses, and characteristics of critical importance to end‐use quality and nutritional value.