This book constitutes the revised refereed summary of the results presented during the European IST/FET proactive initiative's Global Computing workshop, GC 2003, held in Rovereto, Italy, in February 2003.The eight revised full papers and survey articles presented together with a detailed introductory overview assess the state of the art in global computing. Global computing attempts to develop models, frameworks, methods, and algorithms to build systems that are flexible, dependable, secure, robust, and efficient. The dominant technical issues are coordination, interaction, security, safety, scalability, robustness, mobility, risk management, performance analysis, etc.