Three US national laboratories, which were established at the dawn of the Cold War, have long outlived their original mission of engaging in coordinated nuclear weapons research to combat the Soviet threat. But as the nature of the threats has changed, institutional ownership and investments in national security science and technology have failed to keep pace. This overarching misalignment between priorities and investments undercuts the relevance of Los Alamos, Lawrence Livermore, and Sandia National Laboratories in the 21st century. Born in the days of the nuclear arms race, these national labs and the governmental infrastructure above them have clung too tightly to their original nuclear weapons mandate and have failed to reconstitute their efforts to reflect the more diffuse challenges, nuclear and otherwise, facing the country today. Though blame for this lapse could be placed at the feet of policy makers, bureaucrats, and program managers alike, the author writes, the prescription for ameliorating the problem is straightforward: devise and fund a more nimble science, technology, and engineering enterprise that builds upon the unique capabilities at these national labs while outfitting the facilities for, and charging them with, meeting the security and technology challenges of today.