  This volume contains the proceedings of the 11th International Workshop on
Verification of Infinite-State Systems (INFINITY 2009). The workshop was held
in Bologna, Italy on August 31, 2009, as a satellite event to the 20th
International Conference on Concurrency Theory (CONCUR 2009). The aim of the
INFINITY workshop is to provide a forum for researchers interested in the
development of formal methods and algorithmic techniques for the analysis of
systems with infinitely many states, and their application in automated
verification of complex software and hardware systems.
