This book constitutes the refereed proceedings of the 7th International Conference on Combinatorial Optimization and Applications, COCOA 2013, held in Chengdu, China, in December 2013. The 36 full papers presented were carefully reviewed and selected from 72 submissions. The papers feature original research in the areas of combinatorial optimization and its applications. In addition to theoretical results there are reports on experimental and applied research of general algorithmic interest.