This paper describes a hypermedia infrastructure, called HyperDisco, designed to address important issues such as integration, collaboration, versioning, scalability, openness, distribution, heterogeneity, interoperability, extensibility and computation. HyperDisco allows distributed heterogeneous tools to be integrated into a hypermedia environment. Integrated tools can allow the establishment and exploration of hypermedia links between documents of various formats located in information repositories (stores) distributed across Internet domains. HyperDisco supports extension of integrated tools to handle multiple collaborating users and multiple versions of shared documents. Four important capabilities of the HyperDisco prototype (tool integration, tool extension, Internet distribution and interoperability with the World Wide Web) are described and used to evaluate the suitability of HyperDisco as an infrastructure for digital libraries. We conclude by outlining future evaluative and...