Abraham Ibn Ezra’s (ca. 1089-ca. 1161) astrological corpus includes the two versions of Sefer ha-ʿOlam (Book of the World), which represent the first Hebrew theoretical work, unique in medieval Jewish science, to discuss the theories and techniques of historical and meteorological astrology that had accumulated from Antiquity to Ibn Ezra’s time. This article surveys the content of the two versions of Sefer ha-ʿOlam and their most important doctrines as he conceived of them. The relevant material is presented chronologically: (a) the (...) ancient period; (b) the Hellenistic period; (c) Indian and Persian contributions; (d) contributions by astrologers working in the Muslim world; and (e) connections with twelfth-century Latin work on world astrology. In addition, this paper examines the contents of three additional texts by Ibn Ezra, directly concerned with word astrology: (a) the tenth chapter of Reshit Ḥokhmah (Beginning of Wisdom), where Ibn Ezra presents a series of cycles related to world astrology; (b) the astrological section of the exegetical excursus in the long commentary on Exodus 33:21, where Ibn Ezra inserts material on world astrology into his biblical commentary; (c) the introduction to Sefer ha-Moladot (Book of Nativities), where Ibn Ezra juxtaposes world astrology and the doctrine of nativities and presents a series of original ideas about world astrology. (shrink)