Jesuit priests often served as the avant-garde as European powers expanded in the early modern era. Jesuit on the Roof of the World is the first full-length study of Ippolito Desideri, a Jesuit explorer and missionary who traveled in Tibet from 1715 to 1721. Based on close readings of a wide range of primary sources in Tibetan, Italian, and Latin, Trent Pomplun's work follows the Jesuit's journey across Tibet's western deserts, his entry into the court of the Mongol chieftain Lhazang Khan, and his flight during the war that shook the Himalayan kingdom during his stay. Desideri's letters and later account of his travels relate the encounter between his Thomist philosophy and the scholasticism of Geluk monks; the personal conflict between his Roman Catholic beliefs and his appreciation of Tibetan religion and culture; and the political intrigues that led to the establishment of the Chinese protectorate in 1720. Desideri's writings also offer a unique glimpse of Europe's fascination with the land of snows.