This book constitutes the refereed proceedings of the 9th International Conference on Parallel Problem Solving from Nature, PPSN 2006, held in Reykjavik, Iceland in September 2006.

The 106 revised full papers presented were carefully reviewed and selected from 255 submissions. The papers cover a wide range of topics, from evolutionary computation to swarm intelligence and from bio-inspired computing to real-world applications; they are organized in topical sections on theory, new algorithms, applications, multi-objective optimization, evolutionary learning, as well as representations, operators, and empirical evaluation.