This paper discusses the provision of advanced performance support through the integration of techniques used in developing knowledge-based systems, namely diagnostic expert systems and adaptive hypermedia systems. This integration is implemented by employing hypermedia which allows supporting content to be synchronized with the diagnostic expert system inference process. The paper proposes an integrated fault data model for diagnostic expert systems. It also introduces a technique for the adaptive retrieval of hypermediabased technical information using data semantics. A special organisation of displays in the user interface of the adaptive diagnostic expert system allows operators, while applying the expert system for fault diagnosis, to
request detailed information about a certain diagnosis procedure, and then return to the system to continue from where they left off. The techniques proposed in this paper are demonstrated through a prototype adaptive expert system for locating and correcting braking system faults in a forklift truck.