This book constitutes the refereed proceedings of the 9th International Conference on Theory and Applications of Satisfiability Testing, SAT 2006. The book presents 26 revised full papers together with 11 revised short papers and 2 invited talks. Coverage extends to all current research issues in propositional and quantified Boolean formula satisfiability testing. The papers are organized in topical sections on proofs and cores, heuristics and algorithms, and more.