The Atlas Transformation Language (ATL) is being developed by the ATLAS team, INRIA. It is a hybrid language (a mix of declarative and imperative constructions) designed to express model transformations as required by any MDA approach (see the QVT RFP). It is described by an abstract syntax (a MOF meta-model), a textual concrete syntax and an additional graphical notation allowing modelers to represent partial views of transformation models. A transformation model in ATL is expressed as a set of transformation rules. The recommended style of programming is declarative. Transformations from Platform Independent Models (PIMs) to Platform Specific Models (PSMs) can be written in ATL to implement the MDA™ approach as suggested by the OMG.