This book is devoted to the 6th International Conference on Theory and - plications of Satis?ability Testing (SAT 2003) held in Santa Margherita Ligure (Genoa, Italy), during May5 8,2003. SAT 2003followedthe WorkshopsonS- is?ability held in Siena (1996), Paderborn (1998), and Renesse (2000), and the Workshop on Theory and Applications of Satis?ability Testing held in Boston (2001) and in Cincinnati (2002). As in the last edition, the SAT event hosted a SAT solvers competition, and, starting from the 2003 edition, also a Quanti?ed Boolean Formulas (QBFs) solvers comparative evaluation. There...