Eugenics, ‘The science of the improvement of the human race by better breeding,’ was a major force in U.S. science and policy from the last quarter of the 19th century through the first third of the 20th century. Eugenic practices were claimed to represent cutting-edge science. We now know that these claims were false, but during this period eugenics had major effects on U.S. policy. We will review and critique the scientific claims, and show the dire results of these policies, and we point out that several issues that eugenics dealt with are still topics of controversy today. We will discuss how scientists can avoid some of the errors encountered during the era of eugenics.