This special issue of the the Logical Methods in Computer Science (LMCS) journal contains revised and extended versions of papers presented at the 23 rd International Conference on Concurrency Theory (CONCUR'12) which was held in Newcastle upon Tyne, United Kingdom, between 4th and 7th of September 2012.

The eight papers included in this special issue were invited by the guest editors. The selection was based on the evaluation of the papers by the mem bers of the Program Committee and their subreferees, and all submitted papers were peer-reviewed in accordance with the usual high standards of LMCS. The papers reflect the high level of the conference and cover a representative range of topics in its scope.

We would like to thank the authors of papers included in this special issue for their excellent efforts, and the referees for their thorough and care ful work. We would also like to thank LMCS for help and support.