By the late eighteenth century, women wrote books popularizing the major scientific advances of the times. From even an earlier stage, women translated popular science books, many written especially for the “use of the Ladies.” From Aphra Behn’s translation of Fontenelle’s famousEntretiens sur la Pluralité des Mondesin 1686 to Mary Somerville's 1831 lucid exposition in English of Laplace's well-known book,The Mechanism of the Heavens, translation moved gradually toward professional scientific exposition. Who were these women and what sparked their interest in science? How had they acquired the knowledge necessary to translate science books? The aim of this article is to shed some light on a little known area of women's activities—the translation of science books—and to show their contribution to the diffusion of the scientific knowledge.