This is the second of four reports of the Interactive Group Modeling project--an undertaking designed to extend group communication through computers to support the more task-focused communication required by those building computer models. The report focuses on the HUB system--a system that facilitates communication in four modes: computer conferences, shared visual spaces, program workspaces, and document workspaces. Specifically, the report introduces the concept of interactive monitoring of group communication and explores the uses and impacts of the HUB monitor. (FL)