As demonstrated in this issue, the emerging field of microelectromechanical systems (MEMS) is beginning to impact almost every area of science and technology. MEMS have the potential to revolutionize light-wave systems. Microdevices such as optical switches, variable attenuators, active equalizers, add/drop multiplexers (ADMs), optical cross-connects (OXCs), gain tilt equalizers, data transmitters, and many others are beginning to find ubiquitous application in advanced light-wave systems.