The Proceedings of the International Materials Symposium on Ceramic Microstructures ‘86: Role of Interfaces presents a comprehensive coverage of the past decade’s advances in ceramic science and technology related to microstructures. The term microstructure is used in the broad sense and is synonymous with char~cter. Character is defined as a complete detailed description of chemical and physical characteristics of a material. This symposium is the third in a series, held every ten years, on ceramic microstructures. The first symposium, in 1966, had as a subtitle Their Analysis, Significance and Production and emphasized the need and importance of characterization in order to fully understand the chemical and physical properties of materials. The second Symposium, in 1976, placed emphasis on the exploration of characters most suited and needed for Energy-Related Applications. By the time of that conference, the sequence of processing–characterization–properties was fully accepted. It was recognized that characterization was the basis of materials science; the objective of processing was to produce a desired character that was considered necessary to realize a given property or behavior. To further emphasize the importance of character, the symposium dealt primarily with the property/character coupling.