The goal of the IST/FET proactive initiative on Global Computing is to obtain models, frameworks, methods, algorithms to build systems that are flexible, dependable, secure, robust and efficient. The dominant concerns are those of handling the co-ordination and interaction, security, reliability, robustness, failure modes, and control of risk of the entities in the system and the overall design, description and performance of the system itself. Completely different paradigms of computer science may have to be developed to tackle these issues effectively.