international mobility, the US education and research enterprise will have to readjust to be able to keep attracting the best students from home and abroad.

International exchanges of students and skilled professionals can benefit both the sending and receiving countries. Certainly, the United States S&E research enterprise depends critically on international students and scholars. Recommendations that various groups have made to maintain and enhance the ability of the United States to attract these highly skilled people include the following:

• Create new nonimmigrant visa categories exempted from the 214b provision for doctoral-level graduate students and postdoctoral scholars.

• Extend the validity of Visas Mantis security clearances for international students and scholars from the current 2-year limit to the duration of their academic appointments.

• Allow international students, scholars, scientists, and engineers to renew their visas in the United States.

• Implement a points-based immigration policy, similar to that of Canada or the United Kingdom, in which graduate education and S&E skills count toward obtaining citizenship.

The exchange of people and ideas across borders, accelerated in the last two decades by perestroika and the emergence of East Asia as a world economic power, has transformed institutions and individuals. Most countries today send bright young people to study abroad.¹ Many of them stay and contribute in lasting ways to their adopted countries. And whether they stay, return home, or move on to a third country, they become part of a global network of researchers, practitioners, and educators that provides cultural and intellectual support for students and scholars whatever their origins.

Since World War II, the United States has been the most popular destination for S&E graduate students and postdoctoral scholars choosing to study abroad. With about 6% of the world’s population, the United States has been producing over 20% of S&E PhD degrees.² International graduate students and postdoctoral researchers, many of whom stay in the United