Millions of immigrants and refugees change homes each year—driven by natural disaster and economic need; seeking better hopes of freedom, security, economic betterment; or simply looking for a more desirable environment in which to live. Numerous others temporarily relocate in a foreign land in order to serve as diplomats, military personnel, or as employees on overseas assignments for other governmental and intergovernmental agencies. Peace Corps volunteers have worked in more than one hundred nations since the inception of that organization in 1960. Researchers, professors, and students visit and study at foreign academic institutions, and missionaries travel to other countries to carry out their religious endeavors. An increasing number of the employees of multinational corporations work overseas, while individual accountants, teachers, construction workers, athletes, artists, musicians, and writers seek employment in foreign lands on their own.

Individuals such as those mentioned above face...