This book constitutes the refereed proceedings of the 31st International Conference on Applications and Theory of Petri Nets and Other Models of Concurrency, PETRI NETS 2010, held in Braga, Portugal, in June 2010. The 16 revised papers classified as theory papers (10), application papers (2), and tool papers (4) were carefully reviewed and selected from 50 submissions. All current issues on research and development in the area of Petri nets and related models of concurrent systems are addressed, novel tools as well as substantial enhancements to existing tools are presented.