The 8th International Conference on Theory and Applications of Satis?ability Testing(SAT2005)providedaninternationalforumforthemostrecentresearch on the satis?ablity problem (SAT). SAT is the classic problem of determining whether or not a propositional formula has a satisfying truth assignment. It was the ?rst problem shown by Cook to be NP-complete. Despite its seemingly specialized nature, satis?ability testing has proved to extremely useful in a wide range of di?erent disciplines, both from a practical as well as from a theoretical point of view. For example, work on SAT continues to provide insight into various fundamental problems in computation, and SAT solving technology has advanced to the point where it has become the most e?ective way of solving a number of practical problems. The SAT series of conferences are multidisciplinary conferences intended to bring together researchers from various disciplines who are interested in SAT. Topics of interest include, but are not limited to: proof systems and proof c- plexity; search algorithms and heuristics; analysis of algorithms; theories beyond the propositional; hard instances and random formulae; problem encodings; - dustrial applications; solvers and other tools. This volume contains the papers accepted for presentation at SAT 2005. The conference attracted a record number of 73 submissions. Of these, 26 papers were accepted for presentation in the technical programme. In addition, 16 - pers were accepted as shorter papers and were presented as posters during the technicalprogramme.Theacceptedpapersandposterpaperscoverthefullrange of topics listed in the call for papers.