The specification of model adaptation and generation rules is a topic of great interest for the user interface development community, since there are more and more approaches supporting the model-based approach. The ubiquitousness in interaction and the different user profiles are not the only challenges when designing interactive systems. Furthermore, the context of use evolves over time. In this situation, there is a strong need to provide a set of adaptation rules to make the user interface evolve according to the context of use evolution. This paper contributes a metamodel for the definition of adaptation rules in a systematic approach, pursuing engineer adaptation. Moreover, a tool called T:XML is presented that supports the specification of adaptation rules using a visual notation that greatly simplifies the process of designing adaptation for model-based user interface environments. Author Keywords user interface development environment, user interface adaptation, T:XML tool. A...