Plutonium symbolizes everything we associate with the nuclear age. It evokes the entire gamut of emotions from good to evil, from hope to despair, and from the salvation of humanity to its utter destruction. No other element bears such a burden. Its discovery in 1941, following the discovery of fission in 1938, unlocked the potential and fear of the nuclear age. During the Cold War, the primary interest in plutonium was to provide triggers for thermonuclear weapons that formed the basis of nuclear deterrence. Beginning in the 1950s, plutonium also became an integral part of the quest for nearly limitless electrical power. The end of the Cold War has dramatically altered the military postures of the United States and Russia, allowing each to reverse the engines fueling the nuclearweapons buildup. Now, both countries face the challenge of keeping the remaining stockpile of nuclear weapons safe and reliable without nuclear testing, as well as cleaning up nuclear contamination and preventing the spread of nuclear weapons and terrorism. Moreover, current concerns about energy availability and global warming have rekindled interest in nuclear power.