This book constitutes the refereed proceedings of the 12th International Conference on Concurrency Theory, CONCUR 2001, held in Aalborg, Denmark in August 2001.The 32 revised full papers presented together with six invited contributions were carefully reviewed and selected from 78 submissions.

Invited Talks.- Channel Representations in Protocol Verification.- Bigraphical Reactive Systems.- Control of Networks of Unmanned Vehicles.- Process Algebra and Security (Abstract).- Invited Tutorials.- Using the Bandera Tool Set to Model-Check Properties of Concurrent Java Software.- Performance Evaluation:= (Process Algebra + Model Checking) X Markov Chains.- Mobility.- Typing Mobility in the Seal Calculus.- Reasoning about Security in Mobile Ambients.- Synchronized Hyperedge Replacement with Name Mobility.- Dynamic Input/Output Automata: A Formal Model for Dynamic Systems.- Probabilistic Systems.- Probabilistic Information Flow in a Process Algebra.- Symbolic Computation of Maximal Probabilisti Reachability.- Randomized Non-sequential Processes.- Model Checking.- Liveness and Fairness in Process-Algebraic Verification.- Bounded Reachability Checking with Process Semantics.- Techniques for Smaller Intermediary BDDs.- An Algebraic Characterization of Data and Timed Languages.- Process Algebra.- A Faster-than Relation for Asynchronous Processes.- On the Power of Labels in Transition Systems.- On Barbed Equivalences in ?-Calculus.- CCS with Priority Guards.- Probabilistic Systems.- A Testing Theory for Generally Distributed Stochastic Processes.- An Algorithm for Quantitative Verification of Probabilistic Transition Systems.- Compositional Methods for Probabilistic Systems.- Unfoldings and Prefixes.- Towards an Efficient Algorithm for Unfolding Petri Nets.- A Static Analysis Technique for Graph Transformation Systems.- Local First Search — A New Paradigm for Partial Order Reductions.- Extending Memory Consistency of Finite Prefixes to Infinite Computations.- Model Checking.- Abstraction-Based Model Checking Using Modal Transition Systems.- Efficient Multiple-ValuedModel-Checking Using Lattice Representations.- Divide and Compose: SCC Refinement for Language Emptiness.- Unavoidable Configurations of Parameterized Rings of Processes.- Logic and Compositionality.- Logic of Global Synchrony.- Compositional Modeling of Reactive Systems Using Open Nets.- Extended Temporal Logic Revisited.- Games.- Symbolic Algorithms for Infinite-State Games.- A Game-Based Verification of Non-repudiation and Fair Exchange Protocols.- The Control of Synchronous Systems, Part II.