The miniaturization of atomic devices with methods lent from microelectromechanical systems (MEMS) has enabled small, low-power high-performance sensors. Pioneered by the development of the chip-scale atomic clock, the technology has advanced to gyroscopes and optically-pumped magnetometers. At the heart of each device is a MEMS alkali vapor cell. It is integrated with micro-optical components, heaters, photodiodes, and lasers in a miniature package of less than 1cm 3 . MEMS fabrication can open the door for low-cost fabrication in large quantities and make atomic sensors manufacturable with lithographically-defined precision.