Thisis theconferencerecordfortheFifthInternationalConferenceonPrinciples and Practice of Constraint Programming (CP'99), held in Alexandria, Virginia, USA, on October 11-14, 1999. The series of CP conferences deal with original papers on most aspects of constraint programming. After a few annual wo- shops, CP'95 took place in Cassis, France, CP'96 in Cambridge, USA, CP'97 in Schloss Hagenberg, Austria, and CP'98 in Pisa, Italy. Thisyearatotalof97papersweresubmitted, and30wereacceptedasregular papers.In addition, therewerethreeinvitedpapers, byKrzysztofApt, Christian Bessi erre and Benjamin Wah, and eight poster papers, included to showcase yet more interesting directions. The posters appear as short papers in this volume. In the conference, there was an invited tutorial, and following the conference, there were ?ve workshops. All papers were reviewed by an excellent program committeeandtheir designatedreferees.Detailedemaildiscussionsprecededthe actual programcommittee meeting, which was held near the conference location in mid-July, 1999. The CP conferences have had two major directions: constraint satisfaction problems and programming with constraints. This year, the submission/acce- ancebreakdownwassubjectivelyestimatedat56/19and33/8, respectively, with the remaining ratio of 8/3 for application papers. The regional distribution of (?rst) authors for all submissions was 21 for France, 15 for Germany, 12 for USA, 7 for UK, 6 for Japan, 5 for Spain, 4 for Australia and Singapore, 3 each for Italy, Portugal, Sweden, and Switzerland, 2 for Canada and Belgium, and ?nally, one each for Greece, Finland, Hong Kong, Indonesia, Ireland, Korea, and the Netherlands.