by the United States Department of Labor's Bureau of Labor Statistics tracking thousands of Americans starting in the 1980s. Only non-Hispanic whites are included in the analyses so as to demonstrate that the relationships between cognitive ability and social behavior are not driven by race or ethnicity. Herrnstein and Murray argue that intelligence is a better predictor of individuals' outcomes than parental socioeconomic status. This argument is based on analyses where individuals' IQ scores are shown to better predict their outcomes as adults than the socioeconomic status of their parents. Such results are reported for many outcomes, including poverty, dropping out of school, unemployment, marriage, divorce, illegitimacy, welfare dependency, criminal offending, and the probability of voting in elections. All participants in the NLSY took the Armed Services Vocational Aptitude Battery (ASVAB), a battery of ten tests taken by all who apply for entry into the armed services. (Some had taken an IQ test in high school, and the median correlation of the Armed Forces Qualification Test (AFQT) scores and those IQ test scores was .81). Participants were later evaluated for social and economic outcomes. In general, Herrnstein and Murray argued, IQ/AFQT scores were a better predictor of life outcomes than social class background. Similarly, after statistically controlling for differences in IQ, they argued that many outcome differences between racial-ethnic groups disappeared. Values are the percentage of each IQ sub-population, among non-Hispanic whites only, fitting each descriptor. Part III. The National Context This part of the book discusses ethnic differences in cognitive ability and social behavior. Herrnstein and Murray report that Asian Americans have a higher mean IQ than white Americans, who in turn outscore black Americans. The book argues that the black-white gap is not due to test bias, noting that IQ tests do not tend to underpredict the school or job performance of black individuals and that the gap is larger on apparently culturally neutral test items than on more culturally loaded items. The authors also note that adjusting for socioeconomic status does not eliminate the black-white IQ gap. However, they argue that the gap is narrowing. According to Herrnstein and Murray, the high heritability of IQ within races does not necessarily mean that the cause of differences between races is genetic. On the other hand, they discuss lines of evidence that have been used to support the thesis that the black-white gap is at least partly genetic, such