This dissertation addresses the problem of semi-automatically creating schema mappings. The need for developing schema mappings is a pervasive problem in many integration scenarios. Although the problem is well-known and a large body of work exists in the area, the development of schema mappings is today largely performed manually in industrial integration scenarios. In this thesis an approach for the semi-automatic creation of schema mappings based on a central ontology is developed. The central ontology stores domain as well as integration knowledge. Using this ontology as a basis, schema mappings of high quality can be created automatically. In summary, the presented results show that by exploiting background knowledge automatic schema mapping can be developed to a level where it is applicable in complex industrial scenarios. Furthermore, novel knowledge collection approaches complimenting the mapping approach by presenting non-intrusive methods for collecting the required background knowledge from business users are presented.