This book constitutes the thoroughly refereed joint postproceedings of the 8th International Seminar on Relational Methods in Computer Science, the 3rd International Workshop on Applications of Kleene Algebra, and the Workshop of COST Action 274. The 17 revised full papers presented together with 3 invited papers address foundational and methodological aspects of the calculi of relations and Kleene algebra, and their application in various areas of computer science and information processing.