Over the last half-century, numerous alarms have sounded about looming shortages of scientists and engineers in the United States. The implications of such shortages are critical to U.S. growth, competitiveness, and security. To more closely examine whether there is, indeed, an underproduction of scientists and engineers, the authors focus on the production of science and engineering PhDs. They identify and discuss five concepts of shortage. Production might be called low if: (1) it is lower now that it was in the past, (2) competitors' share of total production is growing, (3) it is lower than what people doing the producing would like, (4) less is being produced than the nation is deemed to need, and (5) it is not meeting market demand. They determine that concept (5) is fundamentally different from the others, as it embodies a corrective mechanism that induces increased production of its own accord. They reason that if production of scientists and engineers is too small to fill the growing number of jobs offered, then salary offers will tend to increase and unemployment (or underemployment) of the workforce will increase. This will attract young people into science and engineering careers and any shortage will diminish. The authors identify four strategies to make science and engineering careers more attractive: (1) increase federal funds for research in science and engineering fields, (2) increase incentives for private investment and hiring in science and engineering fields, (3) adopt the "professional school model" for science and engineering PhD programs, (4) introduce two new professional doctoral degree programs for science and engineering built on the MD model The authors caution that increasing the supply of workers without also increasing the number of jobs at least 10 years out will be destabilizing. In addition, they suggest improving the range and timeliness of science and engineering workforce data.