My book Metamorphic Rocks and Metamorphic Belts (in Japanese) was published by Iwanami Shoten, Publishers, in Tokyo in 1965. A few years later, Mr D. Lynch-Blosse of George Allen & Unwin Ltd contacted me to explore the possibility of translating it into English. Thus, translation accompanied by rewriting of substantial parts of the book was made in subsequent years, resulting in the present book Metamorphism and Metamorphic Belts. This title was chosen to emphasize the tectonic Significance of metamorphic belts. Metamorphic geology has a long history. The microscopic description and classification of metamorphic rocks began in the late nineteenth century. The theory of equilibrium mineral assemblages began in the first half of the twentieth century. Detailed mineralogical studies and the experimental determination of the pressure-temperature conditions of metamorphism began in the 1950s. The importance of metamorphic petrology in our understanding of the tectonic processes has been realized only in the past decade. This book is intended to synthesize the mineralogic, petrologic and tectonic aspects of metamorphism. Advanced treatment of the thermodynamic and structural aspects is not intended.