This book undertakes an objective and comprehensive inquiry into the economic consequences of immigration into the United States and concludes that immigration is, on the whole, beneficial to US natives. Among the many novel features of Simon's analysis are a comparison between the received theory of the international movement of goods and the movement of capital, from which he concludes that they are far less similar than supposed; the analysis of the cost of the use of capital by immigrants; the estimate of the cost of use of demographic capital. Although the book is based on experience in the United States, its investigations apply to most of the developed countries.