Ann Macintosh Napier University, UK The papers in this volume are the refereed application papers presented at ES2000, the Twentieth SGES International Conference on Knowledge Based Systems and Applied Artificial Intelligence, held in Cambridge in December 2000. The scope of the Application papers has expanded over recent years to cover not just innovative applications using traditional knowledge based systems, but also to include applications demonstrating the whole range of AI technologies. This volume contains thirteen refereed papers describing deployed applications or emerging applications, together with an invited keynote paper by Dr. Daniel Clancy of NASA Ames Research Centre. The papers were subject to refereeing by at least two "expert" referees. All papers which were controversial for some reason were discussed in depth by the Application Programme Committee. For the application stream, a paper is acceptable even if it describes a system which has not yet been installed, provided the application is original and the paper discusses the kinds of things that would help others needing to solve a similar problem. Papers have been selected to highlight critical areas of success (and failure) and to present the benefits and lessons learnt to other developers. Papers this year cover topics as diverse as: KBS for maintaining offshore platforms; Data Mining to predict corporate business failure; integrated AI techniques to support field service engineers; Natural Language applied to the Data Protection Act; knowledge management and the application of neural networks.