Modern database systems enhance the capabilities of traditional database systems by their ability to handle any kind of data, including text, image, audio, and video. Today, databasesystemsareparticularlyrelevanttotheWeb,astheycanprovideinputtocontent generators for Web pages, and can handle queries issued over the Internet. The eXtensible Markup Language (XML) is used in applications running the gamut from content management through publishing to Web services and e-commerce. It is used as the universal communication language for exchanging music and graphics as well as purchase orders and technical documentation. As database systems increasingly talk to each other over the Web, there is a fa- growingdesiretouseXMLasthestandardexchangeformat.Asaresult,manyrelational database systems can export data as XML documents and import data from XML d- uments and provide query and update capabilities for XML data. In addition, so called native XML database and integration systems are appearing on the database market, whose claim is to be especially tailored to storing, maintaining, and easily accessing XML documents. After the huge success of the?rst XML Database Symposium (XSym 2003) last year in Berlin (already then in conjunction withVLDB) it was decided to establish this symposiumasanannualeventthatissupposedtotakeplaceasanintegralpartofVLDB. Thegoalofthissymposiumistoprovideahigh-qualityplatformforthepresentationand discussion of new research results and system developments. It is targeted at scientists, practitioners, vendors and users of XML and database technologies.