The 12th International Conference on the Principles and Practice of Constraint Programming (CP 2006) was held in Nantes, France, September 24–29, 2006. Information about the conference can be found on theWeb at http://www.sciences. univ-nantes.fr/cp06/. Information about past conferences in the series can be found at http://www.cs.ualberta.ca/˜ai/cp/.

The CP conference series is the premier international conference on constraint programming and is held annually. The conference is concerned with all aspects of computing with constraints, including: algorithms, applications, environments, languages, models and systems. This series of conferences was created to bring together researchers from different disciplines, interested in high-level modeling as well as sound and efficient resolution of complex optimization and satisfaction problems. Based on this interdisciplinary culture, the CP series of conferences is widely open to different communities of researchers interested in constraint satisfaction, SAT, mathematical programming, problem modeling, system design and implementation, etc.

This year, we received 142 submissions. All of the submitted papers received at least three reviews and were discussed in much detail during an online Program Committee meeting. As a result, the Program Committee chose to publish 42 full papers and 21 short papers in the proceedings (the selection rate for this year is 0.30 for full papers and 0.46 for all accepted contributions). Following the standard format for CP, the full papers were presented at the conference in two parallel tracks and the short papers were presented as posters during a dedicated session. This year, one paper was selected by a subcommittee of the Program Committee to receive a best paper award. The subcommittee was composed of Francesca Rossi, Mark Wallace and myself. To illustrate the variety of the topics addressed in the conference, as well as the industrial impact of constraint programming, the conference program also included four invited talks by Shabbir Ahmed, Giuseppe F. Italiano, Jean-Pierre Merlet and Helmut Simonis. An additional invited talk was given by the recipient of the second “Award for Research Excellence in Constraint Programming” given by the Association for Constraint Programming during the conference. Finally, the core of the technical program included three excellent tutorials: “Soft Constraint Solving” by Javier Larrosa and Thomas Schiex, “Constraint Satisfaction for Stimuli Generation for Hardware Verification” by Yehuda Naveh and “Constraint-Based Local Search in Comet” by Laurent Michel and Pascal Van Hentenryck.