Abstract. Model Driven Engineering (MDE) aims to help software deto abstract the system implementations by means of models and meta-models. In Web-based Collaborative Information Systems (WCIS) modelling plays an important role, especially in the user-interface field. In this kind of systems, where groups of users (with different roles) cooperate through distributed user interfaces, and the complexity of interaction between different elements involved in the system (e.g., actors, roles, tasks, interaction rules, etc.) is usually high, MDE could represent a good solution to model evolvable user interfaces. This paper describes a proposal for an interaction meta-model, as a part of a modelevolution methodology for cooperative Graphical User Interfaces (GUI) through Component-Based Development (CBD) approaches. The paper also presents a case study based on an Environmental Management Information Systems (EMIS), where three actors (a politician, a GIS expert, and a technician) cooperate...