Understanding how people in organizations appropriate and adapt groupware technologies to local contexts of use is a key issue for CSCW research, since it is critical to the success of these technologies. In this paper, we argue that the appropriation and adaptation of groupware and other types of advanced CSCW technologies is basically a problem of sensemaking. We analyze how a group of “technology-use mediators” (Orlikowski et al. Org. Sci. (1995) 6(4), 423) in a large, multinational company adapted a groupware technology (a “virtual workspace”) to the local organizational context (and vice versa) by modifying features of the technology, providing ongoing support for users, and promoting appropriate conventions of use. Our findings corroborate earlier research on technology-use mediation, which suggests that such mediators can exert considerable influence on how a particular technology will be established and used in an organization. However, we also find that the process of technology-use mediation is much more complex and indeterminate than prior research suggests. The reason being, we argue, that new, advanced CSCW technologies, such as “virtual workspaces” and other groupware applications, challenge the mediators’ and users’ sensemaking, because the technologies are equivocal and, therefore, open to many possible and plausible interpretations.