This special issue contains extended versions of papers presented at CSL2006, the 15th Annual Conference (and 20th International Workshop) of the European Association for Computer Science Logic, held in Szeged, Hungary, in September, 2006.

The 8 papers collected in this special issue were invited by the guest editors. The selection was made on the basis of the ranking of the papers by the Program Committee and the opinion of the expert reviewers who assisted the Program Committee. The papers reflect the high level of the conference and represent a wide range of topics including automata and logic, finite model theory, model checking, verification, lambda calculus and type theory, and affine logic, as well as the interplay between logic and applications such as security theory and game theory. We are grateful to the authors for their excellent submissions.

All papers were refereed in accordance with the usual high standards of LMCS. We are grateful to the members of the Program Committee of CSL 06 and their subreferees as well as to all those who have served as reviewers of the papers submitted to this special issue. We would also like to thank Jiri Adamek, Executive Editor of LMCS for his assistance and guidance.