The Ninth International Conference on Reliable Software Technologies, Ada- Europe 2004, took place in Palma, Spain, June 14-18, 2004. It was sponsored by Ada-Europe, the European federation of national Ada societies, and Ada- Spain, in cooperation with ACM SIGAda. It was organized by members of the University of the Balearic Islands (UIB). As in past years, the conference comprised a three-day technical program, during which the papers contained in these proceedings were presented, along with vendor presentations. The technical program was bracketed by two tutorial days, when the attendees...