Object-Oriented Information System (OOIS) is an information system that employs object-oriented technologies in system design and implementation. Recent research advances and industrial innovations in distributed system modeling and Internet applications have enabled OOIS design and implementation to be carried out on the basis of new technologies and platforms. This special section on Modeling Object-Oriented Information Systems presents readers with a set of best papers selected from the 7th International Conference on OOIS. Reviews of theories and applications of OOISs are also provided for predicating trends in OOIS modeling.