This book constitutes the refereed proceedings of the 26th International Conference on Architecture of Computing Systems, ARCS 2013, held in Prague, Czech Republic, in February 2013. The 29 papers presented were carefully reviewed and selected from 73 submissions. The topics covered are computer architecture topics such as multi-cores, memory systems, and parallel computing, adaptive system architectures such as reconfigurable systems in hardware and software, customization and application specific accelerators in heterogeneous architectures, organic and autonomic computing including both theoretical and practical results on self-organization, self-configuration, self-optimization, self-healing, and self-protection techniques, operating systems including but not limited to scheduling, memory management, power management, RTOS, energy-awareness, and green computing.