The availability of land bases from which to launch and maintain military, diplomatic, and humanitarian relief operations is becoming increasingly uncertain because of physical or political constraints. The ability to operate from a sea base, therefore, is likely to become more and more important. The Defense Science Board recently concluded that Sea Basing will be a critical future joint military capability and that DOD should proceed to develop such capability. Following the DSB report, the Navy requested that the National Research Council (NRC) convene a workshop to assess the science and technology base, both inside and outside the Navy, for developing Sea Basing and to identify R&D for supporting future concepts. This report of the workshop includes an examination of Sea Basing operational concepts; ship and aircraft technology available to make Sea Basing work; and issues involved in creating the sea base as a joint system of systems.