More than a century and a half after the publication of Charles Darwin's ground-breaking book On the Origin of Species, the theory of evolution through natural selection has been tested and confirmed innumerable times. It is a cornerstone of modern biology. As the evolutionary biologist Theodosius Dobzhansky observed, "nothing in biology makes sense except in the light of evolution." And yet the teaching of evolution in schools continues to come under attack from creationists. Their arguments do not stand up to scrutiny, however. Moreover, the teaching of evolution is constitutionally protected in the U.S. Nevertheless, American science teachers still face considerable pressure to compromise their presentations on this fundamental concept. What is the best way to oppose religiously motivated threats to scientific thinking? Perhaps not surprisingly that, too, is a matter of debate.