Laurent Michel is the Program Chair of the Twelfth International Conference on Integration of Artificial Intelligence (AI) and Operations Research (OR) techniques in Constraint Programming (CP). The conference will be in Barcelona Spain in May. The aim of the conference series is to bring together interested researchers from constraint programming, artificial intelligence and operations research to present new techniques or applications in the intersection of these fields and to provide an opportunity for researchers in one area to learn about techniques in the others. A main objective of this conference series is also to give these researchers the opportunity to show how the integration of techniques from different fields can lead to interesting results on large and complex problems.