This book presents the revised versions of nine invited lectures presented by leading researchers at the fourth edition of the International School on Formal Methods for the Design of Computer, Communication, and Software Systems, SFT 2004, held in Bertinoro, Italy, September 2004. SFM 2004 is devoted to real-time systems. The lectures presented cover formal models and languages for the specification, modeling, analysis, and verification of time-critical systems, the expressiveness of such models and languages, as well as supporting tools and related applications in different domains. The book offers a unique and comprehensive state-of-the-art survey on real-time systems. Researchers and advanced students will appreciate the book as a valuable source of reference and a systematic guide to the use of formal methods for the specification, analysis, and verification of real-time systems.