Evolution is the cornerstone of biology and one of the most powerful, exciting, and well-supported laws in modern science. Evolution transforms biology from a collection of unrelated observations and definitions into a coherent discipline that, among other things, helps people understand life's history and predict answers to important research questions. Nevertheless, and despite its longstanding and overwhelming support by biologists, geologists, and other scientists, the teaching of evolution is again being attacked--not by new discoveries, but by religious activists, politicians, and others intent on undermining science education, academic freedom, and free thought. To many educated people, these attacks on evolution are a bewildering phenomenon. In this article, the author discusses the various forms of attacks by creationists on the teaching of evolution and explains why one should be concerned about attacks on the teaching of evolution. (Contains 20 notes.)