This book describes the theory and practice of inverting seismic data for the subsurface rock properties of the earth. The primary application is for inverting re?ection and/or transmission data from engineering or exploration surveys, but the methods described can also be used for earthquake studies. Seismic Inversion will be of benefit to scientists and advanced students in engineering, earth sciences, and physics. It is desirable that the reader has some familiarity with certain aspects of numerical computation, such as ?nite-difference solutions to partial differential equations, numerical linear algebra, and the basic physics of wave propagation. For those not familiar with the terminology and methods of seismic exploration, a brief introduction is provided. To truly understand the nuances of seismic inversion, we have to actively practice what we preach (or teach). Therefore, computational labs are provided for most of the chapters, and some ?eld data labs are given as well.