The 3rd workshop of the Special Interest Group "Model Driven SoftwareEngineering" (SIG MDSE) on Dec. 11-12, in Berlin, Germany, focused ontransformations, transformation languages and tools. Contributions: Refinement Transformation Support for QVT Relational Transformations, MDA Transformation Languages, Modelling Graphical User Interfaces forembedded Systems, User Interfaces from Task Models, HCI Patterns in theContext of Model Driven Development for Interactive Systems, On-the-flyMDA application modelling using Executable and Translatable UML, AnApplication of the MDSE Principles in IIS*Case, GenGMF - Efficienteditor development for large meta models using the Graphical ModelingFramework, Modelling Behaviour by Activity Diagrams and Complete CodeGeneration, Model-Driven Architecture for an Interactive Ajax MappingPlatform, Customizing the JET2 Template Engine