This book constitutes the refereed proceedings of the 8th International Conference on Foundations of Software Science and Computation Structures, FOSSACS 2005, held in Edinburgh, UK in April 2005 as part of ETAPS.

The 30 revised full papers presented together with 2 invited papers were carefully reviewed and selected from 108 submissions. The papers are organized in topical sections on rule formats and bisimulation, probabilistic models, algebraic models, games and automata, language analysis, partial order models, logics, coalgebraic modal logics, and computational models.