This volume consists of a collection of 28 papers presented at the NATO Advanced Study Institute held July 14-27, 1985 in the beautiful resort at Les Arcs, France. The director of this ASI was A. K. Sood and A. H. Qureshi was the co-director. Since its introduction in the early 1970s the relational data model has been widely accepted. Several research and industrial efforts are being undertaken to develop special purpose database machines to implement the relational model. In addition, database machines are being explored for applications such as image processing and information retrieval. In this NATO-ASI the lecturers discussed special purpose database machine architectures from the viewpoint of architecture and hardware detail, software, user needs, theoretical framework and applications. The papers presented were of two types - regular papers and short papers. The research in database machines is being conducted in several countries. This fact is under­ scored when it is noted that papers in this volume are authored by researchers in France, Germany, Italy, Japan, Portugal, Turkey, U.K. and U.S.A. The first paper discusses the experience and applications of users with a commercially available database machine. In the following eight papers the characteristics of six database machines are discussed. The second, third and fourth papers deal with the RDBM project at the Technical University of Braunschweig (Germany). Zeidler discusses the design objectives, architecture and system design of RDBM. Teich presents the hardware utilized for sorting.