In this volume, a distinguished set of international scholars examine the nature of collaboration between life partners in the sciences, with particular attention to the ways in which personal and professional dynamics can foster or inhibit scientific practice. Breaking from traditional gender analyses which focus on divisions of labor and the assignment of credit, the studies scrutinize collaboration as a variable process between partners living in the nineteenth and twentieth centuries who were married and divorced, heterosexual and homosexual, aristocratic and working-class and politically right and left. The contributors analyze cases shaped by their particular geographical locations, ranging from retreat settings like the English countryside and Woods Hole, Massachusetts, to university laboratories and urban centers in Berlin, Stockholm, Geneva and London. The volume demonstrates how the terms and meanings of collaboration, variably shaped by disciplinary imperatives, cultural mores, and the agency of the collaborators themselves, illuminate critical intellectual and institutional developments in the modern sciences.