This book constitutes the refereed proceedings of the 11th IFIP WG 6.1 International Conference on Formal Methods for Open Object-Based Distributed Systems, FMOODS 2009, and 29th IFIP WG 6.1 Formal Techniques for Networked and Distributed Systems, FORTE 2009, held in Lisboa, Portugal, in June 2009. The 12 revised full papers presented together with 6 short papers were carefully reviewed and selected from 42 submissions. The papers cover topics such as formal verification, algorithms and implementations, modeling and testing, process algebra and calculus as well as analysis of distributed systems.