Immigration legislation in the United States is aimed primarily at Mexican migrants, who account for over half of all undocumented immigrants in the United States. Citizens of Central American and Caribbean countries contribute another 20%. The first section of this booklet traces the development of United States immigration legislation from the late 1800s to the present and examines its impact on immigration from Latin America and the Caribbean. Section two examines the peculiar symbiotic relationship between Mexican labor and American business that developed in the American Southwest during the 34-year rule of Mexican President Porfirio Diaz (1876-1910). The bracero program is also discussed at some length. Section three presents four interviews with undocumented immigrants from Mexico, El Salvador, Nicaragua, and Guatemala. The interviews include information about why the immigrants left their home countries, how they entered the United States, what type of work they do, what major problems they face as undocumented immigrants, how long they plan to stay in the United States, and under what conditions they would return home. The epilogue looks at statistical analyses of the 1980 Census by demographers at the Bureau of the Census. (JHZ)