This volume is based on a NATO Advanced Research Workshop on User-Centred Requirements for Software Engineering Environments held in Bonas, France, in September 1991. The workshop was organized in two halves, one dominated by discussion of usability problems in software engineering and the other by discussion of existing solutions to these problems. The papers in the volume are grouped under four themes: - Design activities and representations for design - Code representation and manipulation - Technological solutions - The impact of design methods and new programming paradigms.