This book constitutes the refereed proceedings of the 4th International Conference on Formal Modeling and Analysis of Timed Systems, FORMATS 2006, held in Paris, France, in September 2006.

The 22 revised full papers presented together with 3 invited talks were carefully reviewed and selected from 50 submissions. The papers cover work on foundations and semantics of timed systems including timed automata, timed Petri nets, timed MSCs, hybrid automata, timed process algebra, timed temporal logics, timed abstract state machines, as well as probabilistic models. There are contributions on techniques, algorithms, data structures, and software tools for analyzing timed systems and resolving temporal constraints such as model-checking, simulation, robustness analysis, scheduling, etc; finally there are articles on applications like real-time software, hardware circuits, and network protocols.