ForewordfromtheProgramChairs These proceedings contain the papers selected for presentation at the 9th - ropean Symposium on Research in Computer Security (ESORICS), held during September 13-15, 2004 in Sophia Antipolis, France. In response to the call for papers 159 papers were submitted to the conference. These papers were evaluated on the basis of their signi?cance, novelty,and te- nicalquality. Eachpaper wasreviewedby at leastthree members of the program committee. The program committee meeting was held electronically; there was an intensive discussion over a period of two weeks. Of the papers submitted, 27 were selected for presentation at the conference, giving an acceptance rate lower than 17%. The conference program also included an invited talk. A workshop like this does not just happen; it depends on the volunteer e?orts of ahostofindividuals. Thereisalonglistofpeoplewhovolunteeredtheirtimeand energy to put together the workshopand who deserve special thanks. Thanks to all the members of the program committee, and the external reviewers, for all their hardwork in the paper evaluation. Due to the large number of submissions the program committee members were really required to work hard in a short time frame, and we are very thankful to them for the commitment they showed with their active participation in the electronic discussion.