Surface micromachining is the fabrication of micromechanical structures from deposited thin films. Although the process dates to the 1960s, this paper will survey its rapid extension over the past few years and its application to batch-fabrication of micromechanisms and of monolithic micro electromechanical systems (MEMS). Two central issues in surface micromachining are: (i) the understanding and control of the material properties of microstructural films, such as polycrystalline silicon, and (ii) the release of the microstructure, for example by wet-etching silicon dioxide sacrificial films, followed by the drying and surface passivation of the microstructure. Recent developments in hinged structures for post-release assembly and high-aspect ratio fabrication of molded parts from deposited thin films promise to extend greatly the capabilities of surface micromachining technology.