The Army Materials and Mechanics Research Center has conducted the Saga more Army Materials Research Conferences, in cooperation with the Metallurgi cal Research Laboratories of the Department of Chemical Engineering and Metallurgy of Syracuse University, since 1954. The purpose of the conferences has been to gather together scientists and engineers from academic institutions, industry, and government who are uniquely qualified to explore in depth a sub ject of importance to the Army, the Department of Defense and the scientific community. Grain size and its control is a major factor governing the behavior of materi als. Knowledge that one can obtain grain sizes in the 10 micron down to sub micron range has established the basis for a new technology. This volume, Ultrafine-Grain Ceramics, addresses itself to the broad areas of: realization of fine-grain ceramics; preparation of ultrafine particle size materials; characterization of ultrafine particles and ultrafine-grain ceramics; processing and behavior of ultra fine-grain ceramics. The technical advice provided by Dr. S. K. Dutta of the Army Materials and Mechanics Research Center during the editing of this book is acknowledged. The continued active interest and support of these conferences by Dr. E. Scala, Director, Lt. Col. Joseph B. Mason, Commanding Officer, and J. F. Sullivan, Deputy Technical Director, of the Army Materials and Mechanics Re search Center is appreciated.