ThisvolumecontainsthepaperspresentedattheTenthInternationalConference on Logic for Programming, Arti?cial Intelligence, and Reasoning (LPAR 2003), heldonSeptember22-26,2003,inAlmaty,Kazakhstan,togetherwiththeFourth International Workshop on Implementation of Logics. There were 65 submissions, of which 8 belonged to the special submission category of experimental papers, intended to describe implementations or c- parisons of systems, or experiments with systems. Each submission was reviewed by at least three program committee members and an electronic program c- mitteemeetingwasheldviatheInternet.Weareverygratefultothe32program committee members for their e?orts and for the quality of their reviews and d- cussions. Finally, the committee decided to accept 27 papers. The program also included ?ve invited talks, by Franz Baader, Serikzhan Badaev, Dexter Kozen, Sergei Goncharov, and Thomas Wilke. Apart from the program committee, we would also like to thank the other people who have made LPAR 2003 possible: the external reviewers and the local organizers Serikzhan Badaev and Anna Romina. The Internet-based submission software and the program-committee disc- sion software were provided by the second co-chair.