Invited Talks.- Interacting in Chaos.- The Viability of Modelling Socially Organised Activity.- Papers Presented.- Deriving Business Object Definitions from User Work Process Models.- Inference and Information A Design Case Study.- An Ontology for Task World Models.- Formal Models for Cooperative Concepts and an Application for En-Route Air-Traffic Control.- The Role of Formal Proof in Modelling Interactive Behaviour.- Validating Semi-Formal Specifications of Interactors as Design Representations.- The Role of Informal Representations in Early Design.- Pragmatic Formal A Case Study in Integrating Formal Methods into the HCl Development Cycle.- The Role of Verification in Interactive Systems Design.- Integrating Rendering Specifications into a Formalism for the Design of Interactive Systems.- Practical Dialogue Refinement.- Which Widgets? Deriving Implementations from User-Interface Specifications.- A Framework for Generating Spatial Configurations in User Interfaces.- Using Model Checking for the Automatic Validation of User Interfaces Systems.- Specification and Verification of Media Constraints using UPPAAL.- Modelling Direct Manipulation with Referent and Statecharts.- Integrating Joint Behaviour and Dialogue Description.- Working Group Discussions.- Discussion Topics for the DSV-IS'98 Working Groups.- Working Group 1 Report.- Working Group 2 Report.- Working Group 3 Report.