This book constitutes the refereed proceedings of the 15th International Conference on Theory and Applications of Satisfiability Testing, SAT 2012, held in Trento, Italy, in June 2012. The 29 revised full papers, 7 tool papers, and 16 poster papers presented together with 2 invited talks were carefully reviewed and selected from 112 submissions (88 full, 10 tool and 14 poster papers). The papers are organized in topical sections on stochastic local search, theory, quantified Boolean formulae, applications, parallel and portfolio approaches, CDCL SAT solving, MAX-SAT, cores interpolants, complexity analysis, and circuits and encodings.