The intricate choreography necessary to do work in organizations requires effective
coordination. This paper uses a variety of data from R & D organizations to describe
informal communication and its functions in organizations. It argues that informal
communication, generally mediated by physical proximity, is crucial for coordination to
occur. Informal communication is frequent in R&D organizations, it aids organizational
members in learning about each other and their work, it supports both production work
and the social relations that underlie it, and it provides a critical facility that collaborators
rely on to start joint work, maintain it, and drive it to conclusion. Without informal
communication, many collaborations would undoubtedly not occur and others would
break up before becoming successful. In this light we present two telecommunication systems designed to support informal communication through artificial proximity. The Video Window system is a wide-screen video teleconferencing system continuously linking public places, and Cruiser is a switched, desk-top video communications system that implements a metaphor of a virtual hallway. Both systems have the potential to support informal communication, but experience with the VideoWindow and analysis of Cruiser suggest that careful attention to implementation detail will determine if they are successful.