One of the current long term goals at the Electronic Visualization Laboratory (EVL) is to create a persistent virtual environment enabling multiple transcontinentally-situated participants to apply collaborative Virtual Reality (VR) over high-speed and high-bandwidth networks connected to heterogeneous supercomputing resources and large data stores. Many of the applications in the GII Testbed at Supercomputing '95 focused on connecting supercomputing resources to VR devices to visualize data from specific scientific problem domains[1]. Our focus, however, was on researching the techniques required to support general collaborative work in persistent virtual environments. These techniques include providing: representations for virtual co-presence; video and audio teleconferencing; virtual VR interfaces; and database technology for sustaining persistence in virtual worlds. These techniques have been showcased in a collaborative design laboratory called CALVIN in which participants at Supercomputing '95 in San Diego and ARPA headquarters in Arlington, Virginia were able to join collectively in an interactive design session.