FOR much of the past two decades, predictions of an impending shortage of scientists and engineers in America have gained increasingly wide currency. The country is failing to produce scientists and engineers in numbers sufficient to fulfill its economic potential, the argument runs. The supposed causes are weaknesses in elementary, secondary, or higher education, inadequate financing of the fields, declining interest in science and engineering among American students, or some combination of these. Thus it is said that the United States must import students, scientists, and engineers from abroad to fill universities and work in the private sector—though even this talent pool may dry up eventually as more foreign nationals find attractive opportunities elsewhere.