With the tremendous success of the Internet, multi-participant real-time applications based on a shared “virtual world” paradigm are bound to develop at a fast pace: multi-user online games, virtual shopping malls, concurrent design applications etc. These applications attempt to give end-users the illusion of being immersed in a conceptually unique shared virtual environment where they can interact in real-time with other users or computer-controlled objects.The critical point is to provide a consistent view of the world to all participants. Classical client-server approaches work well for a limited number of users on a local network, but fail when trying to support large-scale shared virtual worlds with a large number of users on an open network with uncontrolled resources like the Internet.This paper presents the Continuum platform, which aims to offer a software oriented framework for 3D shared worlds, based on a shared object replication model and a set of interfaces describing services. The paper identifies the requirements of such a platform and shows how the architecture of Continuum tries to answer these requirements. Focus is put on the end-user application programmer point of view. An example application illustrates how the framework can be used and specialized.