James Robert Rice (born December 3, 1940) is an American engineer, scientist, geophysicist, and Mallinckrodt Professor of Engineering Sciences and Geophysics at the Harvard John A. Paulson School of Engineering and Applied Sciences, . Rice is known as a mechanician, who has made fundamental contributions to various aspects of solid mechanics. Two of his early contributions are the concept of the J-integral in fracture mechanics and an explanation of how plastic deformations localize in a narrow band. In recent years, Rice has focused on the mechanical processes involved in earthquakes.