This book has grown and evolved from a course I teach at New Mexico Tech, which is taken chiefly by seniors and graduate students in the Earth Sciences. The rapid accumulation of data on plate tectonics, mantle evolution, and the origin of continents in the last decade has necessitated continued updating of the course. The book is written for an advanced undergraduate or graduate student, and it assumes a basic knowledge of geology, biology, chemistry, and physics that most students in the Earth Sciences acquire during their undergraduate education. It also may serve as a reference book for various specialists in the geological sciences who want to keep abreast of scientific advances in this field. I have attempted to synthesize and digest data from the fields of oceanography, geophysics, geology, planetology, and geochemistry, and to present this information in a systematic manner, addressing problems related to the evolution of the Earth's crust and mantle over the last 4 Gy. The role of plate tectonics in the geological past is examined in the light of geologic evidence, and examples of plate reconstructions are discussed. <...>