Many important collaborative applications require the sharing of dynamic visual data that are generated from interactive 3D graphics or imaging programs within a multimedia environment. These applications demand extensive computational and communication costs that cannot be supported by current bandwidth. Thus, suitable techniques have to be devised to allow flexible sharing of dynamic visual data and activities in real time. This chapter first discusses important issues that need to be addressed from four perspectives: functionality, data, communication and scalability. Current approaches for dealing with these problems are then discussed, and pertinent issues for future research are identified.