Grids, P2P and Services Computing, the 12th volume of the CoreGRID series, is based on the CoreGrid ERCIM Working Group Workshop on Grids, P2P and Service Computing in Conjunction with EuroPar 2009. The workshop took place August 24th, 2009 in Delft, The Netherlands. Grids, P2P and Services Computing, an edited volume contributed by well-established researchers worldwide, focuses on solving research challenges for Grid and P2P technologies. Topics of interest include: Service Level Agreement, Data & Knowledge Management, Scheduling, Trust and Security, Network Monitoring and more. Grids are a crucial enabling technology for scientific and industrial development. This book also includes new challenges related to service-oriented infrastructures. Grids, P2P and Services Computing is designed for a professional audience composed of researchers and practitioners within the Grid community industry. This volume is also suitable for advanced-level students in computer science.