This article presents a brief history of uranium enrichment with gaseous centrifugation, a description of the centrifugation process, and a discussion of its potential impact on proliferation of nuclear weapons. The science and technology of the enrichment technique are clearly presented with the aid of diagrams and simple equations. The article considers a typical breakout scenario (how fast a peaceful-use centrifuge plant could be converted to nonpeaceful purposes) and highlights the history of Iran's nuclear technology program as an example of the difficulties associated with controlling centrifuge proliferation. The authors also analyze potential strategies for closing loopholes in order to make it more difficult to use centrifuge enrichment technology for the purpose of producing nuclear weapons.