The book "Enterprise Information Systems" presents a collection of the best contributions from the 9th International Conference on Enterprise Information Systems (ICEIS 2007), which took place in Funchal, Madeira, Portugal. Organized by the Institute for Systems and Technologies of Information, Control and Communication (INSTICC) and the University of Madeira, in collaboration with ACM/SIGMIS and AAAI, this conference created a significant platform for the exchange between researchers, engineers, and practitioners in the field of business applications of information systems. The conference featured five parallel thematic areas covering various aspects of enterprise computing, including databases, artificial intelligence, information system analysis, software agents, and human-computer interaction. The contributions focus on the practical applications of information systems and their benefits for industry and services, bridging the gap between science and business.