Several visitors to the Alta California missions during the early years of the 19th century commented on their colorful interiors and “illuminated walls,” but most of these original wall paintings, produced c. 1810-1825 by Native artisans under the direction of Spanish priests or Mexican-trained artists, were whitewashed in the late 19th century. From 1936-1942, the Federal Art Project’s Index of American Design was involved in the study and restoration of several of these mural programs. Index artists visited the Southern California missions and produced hundreds of photographs, drawings and watercolors of the extant mural programs, as well as of designs they discovered under layers of plaster. In their aim of identifying a “usable past” the Index transformed these mural fragments from regional designs into national motifs. Through case studies of the wall paintings at Southern California missions visited and documented by the Index, I explain how this transformation was attempted through their processes of selection, appropriation, media translation, re-creation, restoration and national promotion. This dissertation, based on research conducted at selected missions, the Santa Barbara Mission Archive Library, the Archives of American Art and the National Gallery of Art in Washington, D.C., will answer the question of how the Index-created archive and federally-sponsored documentation and “restorations” have influenced our contemporary understandings of California mission design as well as the art historical and national value of the California missions themselves.