Science and innovation are central to human progress and national economic success. Currently, the United States invests 2.8% of GDP in research and development, which is supported by a range of public policies. This paper asks whether the United States invests enough. To answer that question, the conceptual case for government intervention and skepticism about that case are reviewed. The paper then turns to systematic evidence, including the very latest evidence, regarding the operation of the science and innovation system and its social returns. This evidence suggests a clear answer: We massively underinvest in science and innovation, with implications for our standards of living, health, national competitiveness, and capacity to respond to crisis.