With great pleasure I welcome you to Oxford and CO 2012, on behalf of the Program and Organizing Committees. As one of a series of biennial international symposia on combinatorial optimization, CO 2012 continues to attract participants from all over the world. It promises to include an excellent array of presentations about the advances of combinatorial optimization in both theory and practice. I hope you will find CO 2012 stimulating for your research and helpful for both new and existing collaborations.