The 3rd workshop of the Special Interest Group "Model Driven Software Engineering" (SIG MDSE) on Dec. 11-12 , in Berlin, Germany, focused on transformations, transformation languages and tools. Contributions: Refinement Transformation Support for QVT Relational Transformations, MDA Transformation Languages, Modelling Graphical User Interfaces for embedded Systems, User Interfaces from Task Models, HCI Patterns in the Context of Model Driven Development for Interactive Systems, On-the-fly MDA application modelling using Executable and Translatable UML, An Application of the MDSE Principles in IIS*Case, GenGMF - Efficient editor development for large meta models using the Graphical Modeling Framework, Modelling Behaviour by Activity Diagrams and Complete Code Generation, Model-Driven Architecture for an Interactive Ajax Mapping Platform, Customizing the JET2 Template Engine.