Verification Model Checking and Abstract Interpretation : 12th International Conference VMCAI 2011 Austin TX USA January 23 25 2011. Proceedings This book constitutes the refereed proceedings of the 12th International Conference on Verification Model Checking and Abstract Interpretation VMCAI 2011 held in Austin TX USA in January 2011 co located with the Symposium on Principles of Programming Languages POPL 2011. The 24 revised full papers presented together with 4 invited talks were carefully reviewed and selected from 71 initial submissions. The papers showcases state of the art research in areas such as verification model checking abstract interpretation and address any programming paradigm including concurrent constraint functional imperative logic and object oriented programming. Further topics covered are static analysis deductive methods program certification debugging techniques abstract domains type systems and optimization.