In science studies the laboratory has been positioned as a privileged place for understanding scientific practice. Laboratory studies foregrounded local spaces of knowledge production in the natural sciences, and in doing so made the laboratory key to social science epistemologies. This article explores how laboratory studies and observational methods have been tied up together in the science and technology studies project of making scientific practice visible. The author contrasts powerful rhetorics of witnessing and revelation in some significant STS texts with (...) the negotiated and partial ways in which observing science work is done in social science practice. Drawing on empirical material generated with bioscientists and social scientists, the article explores how researchers may resist the observational gaze and mark aspects of knowledge work as private and solitary. The author concludes by arguing that epistemologies of vision point to some unsettling parallels between the study of knowledge-making in STS and audit regimes in contemporary research, and considers how both might devalue invisible work. This analysis suggests that there is a need to reconsider the significance of thinking in the ensemble of knowledge production practices for methodological, epistemological, and strategic reasons. (shrink)