ThisvolumecontainstheresearchpaperspresentedatKI2005, the28thGerman Conference on Arti'cial Intelligence, held September 11-14, 2005 in Koblenz, Germany. KI 2005 was part of the International Conference Summer Koblenz 2005, which included conferences covering a broad spectrum of topics that are all related to AI: tableau-based reasoningmethods (TABLEAUX), multi-agent s- tems (MATES), automated reasoningand knowledgerepresentation(FTP), and software engineering and formal methods (SEFM). The Program Committee received 113 submissions from 22 countries. Each paperwasreviewedbythreereferees;afteranintensivediscussionabouttheb- derline papers during the online meeting of the Program Committee, 29 papers were accepted for publication in this proceedings volume. The program included three outstanding keynote talks: Ian Horrocks (U- versityofManchester, UK), LucSteels(UniversityofBrusselsandSony)and- bastian Thrun (Stanford University), who covered topics like logical foundation, cognitive abilities of multi-agent systems and the DARPA Grand Challenge. KI 2005 also included two excellent tutorials: Techniques in Evolutionary Robotics and Neurodynamics (Frank Pasemann, Martin Hulse, ] Ste'en Wis- mann and Keyan Zahedi) and Connectionist Knowledge Representation and Reasoning (Barbara Hammer and Pascal Hitzler). Many thanks to the tu- rial presenters and the tutorial chair Joachim Hertzberg. Peter Baumgartner, in hisroleasaworkshopchair, collected11workshopsfromallareasofAIresearch, whichalsoincludes ameeting ofthe GermanPriorityProgramonKooperierende Teams mobiler Roboter in dynamischen Umgebungen. I want to sincerely thank all the authors who submitted their work for c- sideration and the Program Committee members and the additional referees for theirgreate'ortandprofessionalworkinthereviewandselectionprocess.Their names are listed on the following pages.