This book constitutes the refereed proceedings of the 9th International Conference on Integer Programming and Combinatorial Optimization, IPCO 2002, held in Cambridge, MA, USA, in May 2002. The 33 revised full papers presented were carefully reviewed and selected from a total of 110 submissions. Among the topics covered are scaling algorithms, flow algorithms, combinatorial optimization algorithms, approximate TSP solutions, graph computations, algorithmic geometry, mixed integer programming, network design, logistic scheduling, constraint solving, resource allocation, matching algorithms, and matroid intersection algorithms.