This book will be the first serious monograph about the Retablo de Isabel la Catolica (ca. 1496-1504) painted by Juan de Flanders and Michel Sittow. After tracing the history and critical history of the altarpiece (and publishing some archival material for the first time), it will present the first discussion of attribution to the supported by technical examination of the individual panels, including infrared reflectography and microscopie examination of the painted surface. Technical examination also supports an interpretation of the artists’ treatment of subject matter as being closely related to the religious and political issues that concerned Queen Isabella in the waning years of her reign. The conservatism inherent in the austere painted treatment of the lives of Christ and the Virgin Mary is compared to conservative works of religious literature commissioned by or dedicated to the Queen in the years that the altarpiece was being painted. Finally, a brief catalogue of the surviving twenty-eight panels will restore a degree of narrative coherence to a project that is too little understood in large part because of the early dispersal of its paintings.