The6thInternationalConferenceontheIntegrationofAIandORTechniquesin Constraint Programming for Combinatorial Optimization Problems (CPAIOR 2009) was held in Pittsburgh, USA, May 29-31, 2009. More information about the CPAIOR conference series can be found atwww.cpaior.org. This volume contains the papers and extended abstracts that were presented during the c- ference. In total there were 65 high-quality submissions, including 41 full paper and 24 extended abstract submissions. The full papers re?ect original unpublished work, whereas the extended abstracts can be either original unpublished work or a summary of work published elsewhere. Each full paper was reviewed by at least three Program Committee members, and most extended abstracts by two. After generaldiscussion, the ProgramCommitteeaccepted 20full papersand 10 extendedabstractsforpresentationduringtheconferenceandpublicationinthis volume. The submissions, reviews, discussion, and the proceedings preparation were all handled by the EasyChair system. We thank the Program Committee, as well as the external reviewers, for their hard work. Inadditiontothefullpaperandextendedabstractpresentation, theprogram contained two invited talks, by Eva K. Lee (Georgia Institute of Technology) and Mark Wallace (Monash University). A summary of each invited talk is also included in this volume. Atwo-daytutorialonconstraintprogrammingwasheldbeforetheconference, during May 27-28, 2009. There were four parts to the tutorial: "Introduction to CP Concepts" presented by Peter van Beek, "Modeling in CP" presented by Helmut Simonis, "Combining CP and Operations Research" presented by John Hooker, and "CP Languages, Systems, and Examples" presented by Laurent Michel, Pascal Van Hentenryck, and Paul Shaw. We thank all tutorial speakers for their e?orts. We also thank the tutorial chair Gilles Pesant for his help in organizing this event.