This book constitutes the refereed proceedings of the 27th International Conference on Applications and Theory of Petri Nets and Other Models of Concurrency, ICATPN 2006, held in Turku, Finland in June 2006. The book presents 16 revised full papers and 6 revised tool papers together with 4 invited papers. All current issues on research and development in the area of Petri nets and modeling of concurrent systems are addressed.