Seven years have elapsed since Dr. Renee Ford, editor-in-chief of Materials Technology, first suggested to me to publish a book on Functionally Graded Materials (FGMs). She said that the FGM concept, then largely unknown outside of Japan and a relatively few laboratories elsewhere, would be of great interest to everyone working in the materials field because of its potentially universal applicability. There was no book about FGMs in English at that time, although the number of research papers, review articles, and FGM conference proceedings had been increasing yearly. We discussed what the book should cover, and decided it should present a comprehensive description from basic theory to the most recent applications of FGMs. This would make it useful both as an introduction to FGMs for those simply curious about what this new materials field was all about, and also as a textbook for researchers, engineers, and graduate students in various material fields. The FGM Forum in Japan generously offered to support this publication program. is very difficult for an individual author to write a book that Because it covers such a wide range of various aspects of many different materials, I invited more than 30 eminent materials scientists throughout the world, who were associated with FGM research, to contribute selected topics. I also asked several leading researchers in this field to edit selected chapters: Dr. Barry H. Rabin, then at the U. S.