The USA has been and has remained the world's most important immigration country. The last quarter of the 20th century has been marked by a new mass immigration wave that in absolute size of the immigration flow can be compared to the highest flows in the previous century. This recent migration, however, differs from traditional immigration to America in that it includes a greater ethnic, religious and cultural diversity. The vast majority of today's immigrants, both legal and clandestine, come from Latin American countries, whereas immigration from Europe is now negligible. The massiveness and non-European composition of the immigrants has provoked sharp criticism of the government's immigration policy by opponents of (current) immigration. Nevertheless the political block that supports immigration is strong, so that heated debates for and against immigration continue and a consensus on the question of further immigration strategy can be expected only within the upcoming century. Many feel that the immigration question, along with multiculturalism, is a key theme in America after the end of the "Cold War". The present immigration debates include key questions relating to American social and economic development, as well as the question of cultural and national identity. In order to give readers, less acquainted with current debates on modern immigration in America, the possibility to better follow and understand their present aspects, the author first systematically reviews the basic characteristics of modern immigration flows to America. The following chapters of the article give a critical discussion on the economic, demographic, ecological and cultural questions of immigration. Finally, the author treats the problems of immigration policy, which, in a way, rounds out the discussion and brings him to certain conclusions.