This report responds to a request by the funding agencies (DOE and NSF) to the Nuclear Science Advisory Committee for review and evaluation of the currently supported efforts in nuclear theory and identification of strategies that ensure a strong U.S. nuclear theory program under various funding scenarios. In the 15 years since the last such report, often called the Koonin Report, nuclear theory has expanded vastly in scope. In addition to the traditional areas of nuclear structure and reaction theory, it encompasses wide areas of quantum chromodynamics relating to the structure of hadrons and the properties of hot and superdense nuclear matter, aspects of physics beyond the Standard Model, as well as the astrophysics of collapsed stars and the origin of elements. In spite of this dramatic expansion of the research field, the size of the active research community supported by the agencies has remained roughly constant, mainly due to a sharp decrease in the size of the nuclear theory program at the NSF.