This book constitutes the refereed proceedings of the 4th International Conference on Deductive and Object-Oriented Databases, DOOD '95, held in Singapore in December 1995. Besides two keynote papers by Stefano Ceri and Michael Kifer, the book contains revised full versions of 28 papers selected from a total of 88 submissions. The volume gives a highly competent state-of-the-art report on DOOD research and advanced applications. The papers are organized in sections on active databases, query processing, semantic query optimization, transaction management, authorization, implementation, and applications.