This study examined the various and sundry practices that went into making natural historical knowledge in francophone eighteenth-century Europe. Through diverse manuscript letters, research notes, and drawings, as well as printed texts and engraved images, it reconstructed working relationships among naturalists, and looked especially at the ways people incorporated natural history observation into the daily routines of their households. The project challenged received views about classification as the defining feature of natural history in this period, and about the clear distinction of physical sciences from natural history. The central figure was René-Antoine Ferchault de Réaumur, author of many volumes on insects, among other things, and the definitive authority on natural history in France the middle decades of the eighteenth century. While the project addressed many aspects of Réaumur’s own work in detail, his papers and letters also made possible an exploration of a dispersed and diverse community of observers and collectors spread across Europe and around the world.