This book constitutes the refereed proceedings of the 9th International Workshop on Architectures, Modeling, and Simulation, SAMOS 2009, held on Samos, Greece, on July 20-23, 2009. The 18 regular papers presented were carefully reviewed and selected from 52 submissions. The papers are organized in topical sections on architectures for multimedia, multi/many cores architectures, VLSI architectures design, architecture modeling and exploration tools. In addition there are 14 papers from three special sessions which were organized on topics of current interest: instruction-set customization, reconfigurable computing and processor architectures, and mastering cell BE and GPU execution platforms.