The centuries-old Spanish folk heritage of our Southwest, and its many faceted and enduring influence on the cultural life of the region, has been written about from various rims of observation. This article describes the pioneer studies of Aurelio M. Espinosa on Spanish folklore in the Southwest, with special emphasis on northern New Mexico. Although he made important contributions to the study of Spanish folklore of southern Colorado, Arizona, and California, and to that of Spain, Mexico, and other parts of Spanish America as well, he devoted most of his research and field work to the upper half of New Mexico which is the richest field of Spanish folklore in the Southwest.In viewing the cultural history of New Mexico, Espinosa reminded his readers that its first century as a Spanish colony, the 17th, was the second great century of Spain's Golden Age of arts and letters. With the vigor of Spain's sense of mission in those centuries, her Golden Age radiated to all parts of Spanish America via Mexico City, Lima, and the other principal colonial capitals. At the same time, from the bookshelf and the store of knowledge of the humble missionary, and the folklore of the Spanish settlers, passed down from generation to generation, the spirit of the Golden Age was reflected on the most remote settled frontiers.