In this chapter, we explore various aspects of multimedia conferencing. We look at Shared Windowing systems that permit multiple simultaneous users of an application that runs under a window system. We then look at Shared Applications that have been written with multiple users in mind, and look at managing Shared Data. We then look at Conference Management, and the problem of looking after all the different systems the users may have running. Finally, we examine how we can make use of Multicast to improve the overall efficacy of such a system. <#2192#>#tex2html_wrap4236#<#2192#> There is a lot of hype about multimedia conferencing. The main thing to grasp is that its usefulness increases with the distance you use it over. However, so does its cost (usually exponentially!), and so do cultural and social problems when you try to interact with people that you may never have met, over a limited bandwidth link. <#2193#>#tex2html_wrap4238#<#2193#> The systems described in this chapter were built as part of two European projects between 1989 and 1994. The first was the CAR Project (Communications for the Automotive industry under Race) which looked at computer supported collaborative work for car designers. The second was the MICE Project (Multimedia Integrated Conferencing for Europe).