The Department of the Navy strives to maintain, through its Office of Naval Research (ONR), a vigorous science and technology (S&T) program in those areas considered critically important to U.S. naval superiority in the maritime environment, including littoral waters and shore regions. In pursuing its S&T investments in such areas, ONR must ensure that (1) a robust U.S. research capability to work on long-term S&T problems in areas of interest to the Department of the Navy and the Department of Defense is sustained, (2) an adequate supply of new scientists and engineers in these areas is maintained, and (3) S&T products and processes necessary to ensure future superiority in naval warfare are provided. One of the critical areas for the Department of the Navy is undersea weapons. An Assessment of Undersea Weapons Science and Technology assesses the health of the existing Navy program in undersea weapons, evaluates the Navy’s research effort to develop the capabilities needed for future undersea weapons, identifies non-Navy-sponsored research and development efforts that might facilitate the development of such advanced weapons capabilities, and makes recommendations to focus the Navy’s research program so that it can meet future needs.