Thesearetheproceedingsofthe8thInternational Conference on Logic Progr- mingandNonmonotonicReasoning (LPNMR2005).Followingthepreviousones held in Washington, DC, USA (1991), Lisbon, Portugal (1993), Lexington, KY, USA(1995),Dagstuhl,Germany(1997),ElPaso,TX,USA(1999),Vienna,A- tria (2001) and Ft. Lauderdale, FL, USA (2004), the eighth conference was held in Diamante, Italy, from 5th to 8th of September 2005. TheaimoftheLPNMRconferencesistobringtogetherandfacilitateinter- tions between active researchers interested in all aspects concerning declarative logic programming,nonmonotonic reasoning,knowledge representation, and the design of logic-based systems and database systems. LPNMR strives to enc- pass theoretical and experimental studies that lead to the implementation of practical systems for declarative programming and knowledge representation. The technical program of LPNMR 2005 comprised three invited talks that were given by Jur .. gen Angele, Thomas Eiter and Michael Kifer. All papers p- sented at the conference and published in these proceedings went through a rigorous review process which selected 25 research papers and 16 papers for the system and application tracks. Many individuals worked for the success of the conference. Special thanks are due to all members of the Program Committee and to additional reviewers for their e?orts to produce fair and thorough evaluations of submitted papers. A special thanks is due to the University of Calabria Organizing Committee which made this event possible. Last, but not least, we thank the sponsoring institutions for their generosity. June 2005 Chitta Baral and Nicola Leone Program Co-chairs LPNMR'05 Organization LPNMR 2005 was organized by the Department of Mathematics at the Univ- sity of Calabria, Italy.