This volume contains the proceedings of the Fourth International Conference on Advances in Information Systems (ADVIS) held in Izmir, Turkey, October, 18-20, 2006. This is the fourth conference dedicated to the memory of Professor Esen Ozkarahan, who was one of the pioneers of database machine research and a founder of database systems in Turkey. The main goal of the conference is to bring together researchers from all around the world working in di?erent areas of information systems to share new ideas and represent their latest results. This time we received 120 submissions from 27 countries.The Program Committee selected 38 papers for presentation at the conference. The invited and accepted contributions covered the main research topics – lated to information systems such as information representation and exchange, databases and datawarehouses, Semantic Web and ontologies, data mining and knowledge discovery, information retrieval and knowledge engineering, archit- ture of information systems, and distributed and wireless information systems. All these topics were discussed in detail during the conference. The success of the conference was dependent on the hard work of a large numberofpeople.Wegratefullyacknowledgethemembersofthe Program C- mittee, who helped to coordinate the process of refereeing all submitted papers. We also thank all the other specialists and our additional referees, who reviewed the papers.