This essay considers the place of astrology at the early Tudor court through an analysis of British Library MS Arundel 66, a manuscript compiled for the use of Henry VII (r. 1485–1509) in the 1490s. It argues that an illustration on fol. 201 depicts King Henry being presented with prognostications by his astrologer, William Parron, with the support of Louis, Duke of Orleans, later King Louis XII of France (r. 1498–1515). It considers the activities of three Tudor astrologer courtiers, William Parron, Lewis of Caerleon, and Richard Fitzjames, who may have commissioned the manuscript, as well as the Fitzjames Zodiac Arch at Merton College, Oxford (1497) and the London Pageants of 1501. It concludes that Arundel 66 reflects the strategic cultural investment in astrology and English prophecy made by the Tudor regime at the time of the marriage negotiations and wedding of Arthur, Prince of Wales and Katherine of Aragon, descendant of Alfonso X, the most illustrious medieval patron of the science of the stars.