During the last ten years a lot of concepts have emerged from software engineering. Most of them try to formalize and organize software engineering knowledge at a higher level of abstraction, giving code a secondary role. Model Driven Architecture (MDA), putting the concept of the model on the critical path of software development, is about to change this situation, turning the role of models from contemplative to productive. This paper introduces some problems detected in the process of adoption of MDA methods. The application of MDA for a specific domain, technique, or technology requires the Description of Specialized Modeling Language. Two main techniques provide support for the description of UML extensions, MOF meta-models and UML profiles. The Process of Mapping Description requires good support to identify the elements of the source modeling language that are mapped and the model elements of the destination modeling language that correspond to the source elements. This process require specific solutions.