The 30th Anniversary Conference on Current Trends in Theory and Practice of Computer Science, SOFSEM 2004, took place during January 24-30, 2004, ' in the Hotel VZ M? e? rin, located about 60 km south of Prague on the right shore of Slapsk'ap? rehrada ("Slapy Dam") in the Czech Republic. Having transformed itself over the years from a local event to a fully internat- nal conference, the contemporary SOFSEM tries to keep the best of its winter school aspects (the high number of invited talks) together with multidiscip- narity trends in computer science - this year illustrated by the selection of the following 4 tracks: - Computer Science Theory (Track Chair: Peter Van Emde Boas) - Database Technologies (Track Chair: Jaroslav Pokorny) ' - Cognitive Technologies (Track Chair: Peter Sin? c' ak) ? - Web Technologies (Track Chair: Julius ' Stuller) Its aim was, as always, to promote cooperation among professionals from a- demia and industry working in various areas of computer science.