This book analyzes the economic effects on immigrants who have gone to the US in order to improve their economics lot. The main findings of this book are intended to answer the question - "how many immigrants should the US admit each year?". The general conclusion, based on the auther's various analyses and findings, is: "more than at present, and chosen more for their economic characteristics and less on the basis of family connections."
This book gives the statistical figures about the size and "quality" of the immigration in US. The immigrants has a smaller share of foreign-born persons than countried thought to be. As to the "quality" of immigrants, immigrants tend to arrive in their 20s and 30s. On average, they have as much education as do natives. Compared to natives, the immigrants' rate of participation in the labor force is higher, they save more, they apply more effort during working hours, they more like to start new businesses and to be self-employed, their rate of unemployment is lower, their fertility rate is lower, and they do not have a higher propensity to commit crime.
The presence of more immigrants means that there are more working persons who will think up productivity. Larger population increases productivity. The most powerful argument against admitting immigrants always is that they take away jobs held by natives and increase native unemployment. However, the author of this book disagree with this point. Immigrants not only take jobs, they make jobs indirectly with their spending and directly with starting new business.
I think this book is outdated. It published 6 years ago. The situation may be changed within this 6 years. But, this book did many good economic researches.