The seismic ray method plays an important role in seismology, seismic exploration, and in the interpretation of seismic measurements. Seismic Ray Theory presents the most comprehensive treatment of the method available. Many new concepts that extend the possibilities and increase the method's efficiency are included. The book has a tutorial character: derivations start with a relatively simple problem, in which the main ideas are easier to explain, and then advance to more complex problems. Most of the derived equations are expressed in algorithmic form and may be used directly for computer programming. This book will prove to be an invaluable advanced text and reference in all academic institutions in which seismology is taught or researched.