Abstract. This paper proposes a framework for transforming and integrating heterogeneous XML data sources, making use of known correspondences from them to ontologies expressed in the form of RDFS schemas. The paper first illustrates how correspondences to a single ontology can be exploited. The approach is then extended to the case where correspondences may refer to multiple ontologies, themselves interconnected via schema transformation rules. The contribution of this research is an XML-specific approach to the automatic transformation and integration of XML data, making use of RDFS ontologies as a `semantic bridge'.