The evolution of software systems can produce incompatibilities with existing data and applications. For this reason, changes have to be well-planned, and developers should know the impact of changes on a software system. This also affects the branch of model-driven development, where changes occur as modification of the metamodels that the system is based on. Models that are instantiated from an earlier metamodel version may not be valid instances if the new version of a metamodel. Also, changes in the interface definition may require adaptations to the modeling tools. In this thesis, the impact of meta-model changes is evaluated for the modeling standards Meta Object Facility (MOF) and the interface definition Java Metadata Interface (JMI), based on the Modeling Infrastructure (MOIN) project at SAP, which includes a MOF- based repository and implements the JMI standard. For the formalisation of changes to MOF-bases metamodels, a Change Metamodel is introduced to describe the transformation of one version of a metamodel to another by the means of modeling itself. The changes are then classifed by their impact on the compatibility o ... mehrf existing model data and the generated JMI interfaces. The description techniques and change classifications presented in this thesis can be used to implement a mechanism that allows metamodel editors to estimate the impact of metamodel changes with the help of modeling tools that can adapt existing data semi-automatically.