With approximately 17490 well-defined modeling objects, the SKO -Datenmodell is probably the most extensive reference data model in German for the banking area. So far, this reference data model has been used in about 30 projects describing different subject areas. The detailed project data models that have been derived from these projects have been reintegrated into the generic reference data model, as far as the results are applicable to the entire Sparkassen-organisation. The SKO-Datenmodell was initially developed approximately 15 years ago. It is derived from the Financial Services Data Model (FSDM), which has been provided by IBM. The FSDM is a reference data model which is generally valid for the banking area. In contrast to the FSDM, the SKO-Datenmodell is specialized for the requirements of the Sparkassenorganisation. The basic elements of the reference data model are a conceptual design of data model abstraction levels, an extensive Methods and Procedures Handbook with precise quality requirements and an integrated tool support by m1 and Rochade . The different levels of the SKO-Datenmodell and the use of these levels in practice are described in this chapter.