abstract: against the background of humanities writing about animal agency, this article examines primatologist Tetsuro Matsuzawa’s work with his‘research partner’, the chimpanzee Ai, and her conspeci cs at the Kyoto University Primate Research Institute and in an outdoor laboratory in Guinea from 1976 to 2016. This latest chapter in the history of Japanese primatology describes an attempt at synthesizing benchwork and eldwork. It examines how what both humans and chimpanzees can do varies across a whole spectrum of scienti c practices, bridging the gap between controlled experiments and eld observations. While some recent animal studies literature has presented laboratory animals as deprived of agency and thereby implicitly attributed agency to creatures of the wild, this historical and ethnographic account does not take the analytic category of agency for granted, but examines how Japanese primatologists think about the ways in which chimpanzees interact with each other, with humans and with their environment.