This book constitutes the refereed proceedings of the 23rd International Conference on Logic Programming, ICLP 2007, held in Porto, Portugal, September 8-13, 2007.

The 22 revised full papers together with 2 invited talks as well as 15 poster presentations and the abstracts of 5 doctoral consortium articles were carefully reviewed and selected from 74 initial submissions. The papers cover all issues of current research in logic programming - they are organized in topical sections on theory, functional and constraint logic programming, program analysis, answer-set programming, semantics, and applications.