The Third International Conference onUnconventional Models of C- putation,UMC2002 was organized by the Center for Discrete Mathematics andTheoreticalComputerScienceandtheKansaiAdvancedResearchCenterof the Communications Research Laboratory, Kansai, Japan. The venue was held in the “unconventional” multipurpose Orbis Hall from 15 to 19 October 2002. Being part of the Kobe Fashion Museum, a disk-shaped building in the center of Kobe’s Rokko Island, the Hall is conveniently located near the Hotel Plaza Kobe and the Kobe Bay Sheraton hotel. Various natural processes motivate the construction of radically new models of computation. For example, the paper “Not Just a Pretty Face” published in the July 27, 2002 issue ofNewScientist discusses the hypothesis that plants mayhavethepowertocomputewithoutthebene?tofabrain. Thispromptsthe question of what sort of computation capability and complexity human bodies may be capable of, even without the help of the nervous system. Although th- ving, the realization of powerful unconventional models of computing is still at an early stage in its development, and a huge and concerted e?ort is required to assess and exploit its real potential. This volume reports the main ideas, results, directions of research, and open questions, discussed at a highly intellectual g- hering of leaders in this new ?eld of research. The ?ow of discussion varies from theoretical aspects to practical implementations and philosophical re?ection. Theeightinvitedspeakersattheconferencewere:M. L. Campagnolo(Lisbon, Portugal), J. Copeland (Canterbury, New Zealand), A. DeHon (CalTech, USA), M. Ogihara (Rochester, USA), M. Ohya (Japan), M. Ozawa (Tohoku, Japan), P. Siwak (Poznan, Poland), and T. To?oli (Boston, USA). TheProgramCommittee,consistingofL. Accardi(Roma,Italy),C. S.