In 1874–75 American Protestant missionaries in Beirut published two astronomy textbooks in Arabic. While male students at the Syrian Protestant College studied Cornelius Van Dyck’s Foundations of Astronomy, girls at secondary schools—the highest level of female education—studied Eliza Everett’s Principles of Astronomy: For Use in Schools. These texts appeared at the height of a cross-cultural encounter between American Protestants and the inhabitants of Beirut and Mount Lebanon that added new meanings to the Arabic concept of science (ʿilm). Historians have analyzed men’s discussions to chart how ʿilm, once a broad category akin to “knowledge” in English, came to include a neo-Baconian understanding of the modern English “science.” This article turns to science pedagogy, a field that included both men and women, to argue that the conceptual transformation of ʿilm also entailed an epistemological division along lines of gender and age. Overall, the story reveals how a study of women in science sheds light on the gendered history of science in Arabic.