This report is the result of a workshop conducted by the Committee on Seismology of the National Research Council to review the field of seismology, its importance in many and diverse areas of national interest, and its future course. This report is intended to be useful not only to the scientific and technical communities but also to the decision-makers who are seeking solutions to critical national problems. This report may also be of use to earth science teachers and school guidance personnel as a supplemental reference in the field of seismology. The report reviews the history, accomplishments and status of seismology; assesses changing trends in seismological research and applications; and recommends future directions in the light of these changes and of the growing needs of society in areas in which seismology can make significant contributions. (MR)