This book constitutes the refereed proceedings of the 9th International Conference on Theory and Applications of Satisfiability Testing, SAT 2006, held in Seattle, WA, USA in August 2006 as part of the 4th Federated Logic Conference, FLoC 2006.The 26 revised full papers presented together with 11 revised short papers presented together with 2 invited talks were carefully selected from 95 submissions. All current research issues in propositional and quantified Boolean formula satisfiability testing are covered; the papers are organized in topical sections on proofs and cores, heuristics and algorithms, applications, SMT, structure, MAX-SAT, local search and survey propagation, QBF, as well as counting and concurrency.