Hypertext systems have gained acceptance in a wide range of application domains (e.g. CASE. systems design, outline processors etc.). However, in order to function effectively in these domains, hypertext systems must support versioning. In this paper we will examine the issues involved in providing versioning facilities that not only support but enhance the special features provided by hypertext. We analyse the requirements that should be satisfied by a versioning system and we examine how existing hypertext systems cope with these requirements. We then describe a set of mechanisms that are powerful enough to comply with our requirements. Finally, we present a demonstration system that will be used to evaluate the effectiveness of our versioning mechanisms.