This book constitutes the refereed proceedings of the Third International Conference on High Performance Computing and Communications, HPCC 2007, held in Houston, USA, September 26-28, 2007. The 75 revised full papers presented were carefully reviewed and selected from 272 submissions. The papers address all current issues of parallel and distributed systems and high performance computing and communication as there are: networking protocols, routing, and algorithms, languages and compilers for HPC, parallel and distributed architectures and algorithms, embedded systems, wireless, mobile and pervasive computing, Web services and internet computing, peer-to-peer computing, grid and cluster computing, reliability, fault-tolerance, and security, performance evaluation and measurement, tools and environments for software development, distributed systems and applications, database applications and data mining, biological/molecular computing, collaborative and cooperative environments, and programming interfaces for parallel systems.