This book is the outcome of an international research seminar on objects, agents, and features held at Dagstuhl Castle, Germany in February 2003.In recent years, concepts in object-oriented modeling and programming have been extended in variuos directions, giving rise to new paradigms such as agent-orientation and feature orientation. This book explores the relationship between the original paradigm and the two new ones.The 12 revised full papers presented together with an introductery overview by the volume editors were carefully reviewed and improved for publication. Among the topics addressed are agent coordination in object-orientation, feature orientation, components and feature interaction, software evolution, agent modeling and analysis, agent interaction, component-based systems, formal specification of agents, and feature engineering.