Thisvolumecontainspapersselectedforpresentationatthe2004AnnualConf- enceoftheEuropeanAssociationforComputerScienceLogic, heldonSeptember 20 24, 2004 in Karpacz, Poland. The CSL conference series started as the International Workshops on C- puterScienceLogic, andthen, after?vemeetings, becametheAnnualConference of the European Association for Computer Science Logic. This conference was the 18th meeting, and the 13th EACSL conference. Altogether 99 abstracts were submitted, followed by 88 papers. Each of these paperswasrefereedbyatleastthreereviewers.Then, afteratwo-weekelectronic discussion,...