The Bell Curve
The Bell Curve: Intelligence and Class Structure in American Life is a 1994 book by Richard J. Herrnstein and Charles Murray exploring the relationship between intelligence and success in American life.  Critics attacked the authors relentlessly over the book's findings.
The book makes two controversial points:
- That in America intelligent people are more successful than average people, and that unintelligent people make more trouble than average people.
- That some ethnic groups have consistently scored lower on intelligence tests, and that cultural bias in the tests fails to explain this
Quotations about the book
Milton Friedman said:
- This brilliant, original, objective, and lucidly written book will force you to rethink your biases and prejudices about the role that individual difference in intelligence plays in our economy, our policy, and our society. 
Steve Sailer wrote,
- It ignited controversy by arguing that IQ scores are one of the most overlooked tools for understanding how American society is structured. 
Murray himself said:
- The reality of a cognitive elite is becoming so obvious that I wonder if even critics of the book really doubt it. The relationship of low IQ to the underclass? Ditto. Welfare reform is helping the argument along, by the way, as journalistic accounts reveal how many welfare mothers are not just uneducated, but of conspicuously low intelligence. The intractability of IQ? Dick and I said that IQ was 40 to 80 per cent heritable. The identical-twin studies continue to suggest that the ultimate figure will turn out to be in the upper half of that range. More importantly, the literature on 'nonshared environment' has developed dramatically since Dick and I were researching The Bell Curve. Its core finding is that, whatever the role of environment may be in determining IQ, only a small portion of that role consists of influences that can be manipulated (through better child-rearing, better schools, etc.). For practical purposes, the ability of public policy to affect IQ is probably smaller than Dick and I concluded. 
- Slate review - makes some thoughtful points