My project aims to explore hitherto overlooked and understudied Ottoman astrological texts produced and disseminated throughout the late-fifteenth and sixteenth centuries, a significant period of time that not only witnessed the fall of Constantinople, the fall of Granada and imposition of confessional uniformity in Spain, the Columbian discoveries, the Protestant Reformation, and Ottoman victories on all fronts, but also coincided with the last years of the Islamic millennium. During this period of apocalyptic and millenarian excitement, eschatological tension took firm hand in the entire Mediterranean. My research will set out from the hypothesis that the fifteenth- and sixteenth-century apocalyptic visions in the Ottoman lands of Eastern Mediterranean were closely related to, and in some measure developed in conversation with the apocalyptic ferment among Christian and Jewish communities in the Western Mediterranean. I argue that it is this common apocalyptic idiom in the Mediterranean that facilitated the wide production of contemporary Ottoman astrological ephemera and its open circulation within both Ottoman territories and Latin Christendom. This astrological material consists primarily of calendars and annual astrological compendia, horoscopes and nativity books prepared for members of the imperial family, and related miscellanies that incorporate fragments of astrological tracts and tables. While significant amount of these materials are now kept in the Palace Library in Istanbul, a great many others are scattered in several manuscript libraries in Europe, especially in cities most directly affected by Ottoman expansionism in the fifteenth and sixteenth century. The preponderance in European libraries of royal horoscopes and annual astrological prognostications would also suggest that contemporary European readers may have used these Ottoman texts as part of the broader information-gathering and espionage activities widespread in early modern Mediterranean