Adolf Hitler didn''t think much of the United States, but during his rise to power he repeatedly singled out one aspect of American life for praise: our eugenic policies.

In Mein Kampf, Hitler applauded America''s exclusionary immigration laws. He carefully studied American laws allowing sterilization of the "unfit" on eugenic grounds. He even wrote fan letters to leading American eugenicists."

In recent years, historians such as Daniel Goldhagen have made a cottage industry of finding new ways to blame Germans for the Holocaust. Black, by contrast, keeps finding new ways to put the onus on Americans. His latest book, War Against the Weak, offers a fierce, compelling, overlong account of how American ideas helped inspire--if that''s the right word--Hitler''s Final Solution.

Eugenics was born in England; Francis Galton coined the term, which is Greek for "well born," in the 1880s. But it was Americans who put into practice Galton''s theory that society should encourage healthier people to have more children and unhealthier ones to have fewer. Alarmed by increased immigration and by the huge native black population, America''s elite discovered in eugenics a "scientific" basis for their belief in white, Northern European supremacy. So at the turn of the 20th century, scientists devised grand schemes to improve the American "protoplasm": They would segregate, sterilize, and perhaps even murder those deemed "un-fit"--as much as 10 percent of the population.

American eugenicists persuaded the Harriman, Carnegie, and Rockefeller families to fund a vast eugenic campus at Cold Spring Harbor, Long Island. Researchers were dispatched to asylums, prisons, hospitals, and poor towns to collect family histories of the supposedly unfit--the mentally ill, the disabled, epileptics, alcoholics, criminals, the immoral, and pretty much anyone else they wanted to throw in. These reports were then collected at the Eugenics Record Office.

Throughout the ''20s, eugenicists pushed draconian immigration restrictions through Congress and persuaded most states to pass laws permitting the sterilization of the unfit. The Supreme Court laid the capstone on these laws in 1927 when Buck v. Bell affirmed the sterilization of a supposedly feeble-minded unwed teenage mother. Justice Oliver Wendell Holmes concluded, "It is better for all the world, if instead of waiting to execute degenerate offspring for crime, or to let them starve for their imbecility, society can prevent those who are manifestly unfit from continuing their kind."

Eugenic sterilization, rare before Buck v. Bell, became commonplace. Eventually America would sterilize more than 60,000 citizens based on shoddy pretenses, including supposedly voluntary operations on children.

Americans

exported their eugenic activism to the world. Sterilization laws sprang up throughout Northern Europe. German eugenicists, particularly captivated by the American notion of Nordic supremacy, published textbooks based on American ideas; Hitler read them. The Rockefeller Foundation funded eugenic experiments in Germany through the early 1930s. Black doesn''t try to claim that American eugenics created Hitler''s evil: Rather, he says, American science allowed Hitler to medicalize and sanitize his hatred, making it palatable for a mass audience.

When Hitler took power, he immediately unleashed American-influenced eugenic policies on Germany. He established eugenic courts modeled on ours, but quickly outstripped his American models. Sterilization led rapidly to the outright murder of the mentally ill. Then, married to anti-Semitism, eugenics devolved into genocide.

War Against the Weak is well told and extraordinarily sad. It represents a prodigious feat of reporting, as Black has trolled every archive and read every letter. And it is a very persuasive book, except perhaps on one count. Black, in his effort to convict Americans as Hitler''s accomplices, may overstate our role in the German genocide. He notes but does not emphasize that as early as the 1920s, many Americans were protesting eugenic policies. When the Nazi scalpels started flying in 1933, American scientists, with the exception of a few hardcore racists, were already abandoning the creed. Once they saw what the Nazis were doing, Americans wanted no part in the game; but their shame was too little, too late.

Edwin black''s War Against the Weak: Eugenics and America''s Campaign to Create a Master Race is available at local bookstores.