Maxwell’s Demon is a thought experiment, first proposed by James Clerk Maxwell in 1871 as a way to reduce the entropy of gas-phase particles by means of an “intelligent creature with deft hands.” We have realized this thought experiment in the laboratory with a self-acting one-way wall for atoms, as originally suggested by Maxwell. This construction has been used to cool atoms, and may be an alternative to evaporative cooling. It is also used for efficient isotope separation with important medical applications that are being pursued at the non-profit Pointsman Foundation, www.pointsman.org