The IXION multimedia, distributed system infrastructure is introduced, and its model of synchronous group work support is described. The model of group work is composed of a small number of simple abstractions within the IXION computational model. These are fully integrated into the infrastructure layers, and the degree of integration extends to full multimedia capability for distributed group work. The model allows existing single user applications to be used by groups of users, as well as providing assistance with the implementation of new, purpose built group applications.