This volume gives the proceedings of the Workshop on User Interface Management Systems and Environments held at INESC, Lisbon, Portugal, June 4-6, 1990. The main impetus for the workshop came from the Graphics and Interaction in ESPRIT Technical Interest Group of the European Community ESPRIT Programme. Several of the foundational concepts in User Interface Management Systems (UIMS) were established at the Eurographics workshop held in Seeheim in November 1983 with well-known proceedings published in this series. In the meantime, the development of windowing systems, object-oriented methodologies and AI-inspired techniques has proceeded on a scale which was hard to anticipate a few years ago. The purpose of this workshop was to re-examine the basic notion of a UIMS and to question its continued appropriateness in the context of current and probable future systems. This entailed an attempt to relate the notion to the newer paradigm of a "user interface development environment" and an assessment of the impact of "knowledge engineering" both in the interface and in the application.