This book constitutes the refereed proceedings of the 11th International Conference on Formal Engineering Methods, ICFEM 2009, held in Rio de Janeiro, Brazil, December 2009.
The 36 revised full papers together with two invited talks presented were carefully reviewed and selected from 121 submissions. The papers address all current issues in formal methods and their applications in software engineering. They are organized in topical sections on Testing, Protocols, verification, model checking, object-orientation, event-b, compilation, process algebra, refinement, algebraic specifications and real-time systems.