This volume was primarily intended to present selected papers from the workshop on Theory and Applications of Nested Relations and Complex Objects, held in Darmstadt, FRG, from April 6-8, 1987. Other papers were solicited in order to provide a picture of the field as general as possible. Research on nested relations and complex objects originates in the late seventies. The motivation was to obtain data models and systems which would provide support for so-called complex objects or molecular structures, i.e., for hierarchically organized data, thereby overcoming severe shortcomings of the relational model. This theme of research is now maturing. Systems based on those ideas are beginning to be available. Languages of various natures (algebras, calculi, graphical, logic-oriented) have been designed and a theory is slowly emerging. Finally, new developments in database technology and research are incorporating features of models involving complex objects. A variety of approaches is represented in this volume. The first three papers give overviews of major pioneering implementation efforts. The fourth paper is devoted to the important issue of implementation of storage structures. The next three papers propose excursions in the foundations of nested relations and complex objects. The following six contributions are all devoted to modeling of complex objects. The area of database design is represented by the last four papers.