A vast body of literature dealing with bubbles, drops, and solid particles has grown up in engineering, physics, chemistry, geophysics, and applied mathematics. The principal objective of this book is to give a comprehensive critical review of this literature as it applies to the fluid dynamics, heat transfer, and mass transfer of single bubbles, drops, and particles. We have tried primarily to provide a reference text for research workers concerned with multiphase phenomena and a source of information, reference, and background material for engineers, students, and teachers who must deal with these phenomena in their work. In many senses, bubbles and drops are the chemical engineer's elementary particles. Inevitably the book has a bias toward the concerns of chemical engineers since each of the authors is a chemical engineer. However, we have attempted to keep our scope sufficiently broad to be of interest to readers from other disciplines. It became clear to us while preparing this book that workers in one area are commonly oblivious to advances in other fields. If this book does no more than bring literature from other fields to the attention of research workers, it will have accomplished part of our purpose.