The Vienna Summer of Logic in July 2014 attracted a great number of researchers working in logic to Vienna. To take advantage of this unprecedented confluence of logicians, especially those working in computational logic, the organizers of the CSL and LICS series of meetings decided to merge the 2014 editions of these meetings into one meeting titled the Joint Meeting of the Twenty-Third EACSL Annual Conference on Computer Science Logic (CSL) and the Twenty-Ninth Annual ACM/IEEE Symposium on Logic in Computer Science (LICS). This joint meeting had one program committee, one program, and one proceedings.

A small number of papers from the proceedings were selected and their authors were invited to submit a full version of their paper to this special issue. All submissions were refereed according to the usual standards of LMCS with each paper being reviewed by three experts in the field. We are grateful to the authors for their excellent submissions and to the reviewers for their efforts to evaluate and improve these papers.