This book constitutes the thoroughly refereed proceedings of the 20th International Symposium on Static Analysis, SAS 2013, held in Seattle, WA, USA, in June 2013. The 23 revised full papers presented together with 2 invited talks were selected from 56 submissions. The papers address all aspects of static analysis, including abstract domains, abstract interpretation, abstract testing, bug detection, data flow analysis, model checking, new applications, program transformation, program verification, security analysis, theoretical frameworks, and type checking.