These proceedings contain the papers presented at the 5th Annual Genetic and EvolutionaryComputationConference(GECCO2003).Theconferencewasheld in Chicago, USA, July 12-16, 2003. A total of 417 papers were submitted to GECCO 2003. After a rigorous doubleblind reviewing process, 194 papers were accepted for full publication and oral presentation at the conference, resulting in an acceptance rate of 46.5%. An additional 92 submissions were accepted as posters with two-page extended abstracts included in these proceedings. This edition of GECCO was the union of the 8th Annual Genetic Progr- mingConference(whichhasmetannuallysince1996)andthe12thInternational Conference on Genetic Algorithms (which, with its ?rst meeting in 1985, is the longest running conference in the ?eld). Since 1999, these conferences have m- ged to produce a single large meeting that welcomes an increasingly wide array of topics related to genetic and evolutionary computation. Possibly the most visible innovation in GECCO 2003 was the publication of theproceedingswithSpringer-VerlagaspartoftheirLectureNotesinComputer Science series.This will make the proceedings available in many libraries as well asonline,wideningthedisseminationoftheresearchpresentedattheconference. OtherinnovationsincludedanewtrackonCoevolutionandArti?cialImmune Systems and the expansion of the DNA and Molecular Computing track to include quantum computation. In addition to the presentation of the papers contained in these proceedings, the conference included 13 workshops, 32 tutorials by leading specialists, and presentation of late-breaking papers. GECCO is sponsored by the International Society for Genetic and Evolut- nary Computation (ISGEC). The ISGEC by-laws contain explicit guidance on the organization of the conference, including the following principles: (i)GECCOshouldbeabroad-basedconferenceencompassingthewhole?eld of genetic and evolutionary computation.
