[Excerpt] Four major principles currently underlie U.S. policy on legal permanent immigration: the reunification of families, the admission of immigrants with needed skills, the protection of refugees and asylees, and the diversity of immigrants by country of origin. These principles are embodied in the Immigration and Nationality Act (INA) and are reflected in different components of permanent immigration. Family reunification occurs primarily through family sponsored immigration. U.S. labor market contribution occurs through employment based immigration. Humanitarian assistance occurs primarily through the U.S. refugee and asylee programs. Origin country diversity is addressed through the Diversity Immigrant Visa.