Micromachined accelerometer developments have been ever increasing due to the demand for smaller size and lower cost with greater performance. The automotive industry used to be the dominating market, but now use of microaccelerometers is booming in portable electronics, video games, health care, and structural vibration monitoring. This chapter provides a comprehensive review of the operational principles of various acceleration sensing mechanisms, and is accompanied with a review of different fabrication technologies and topological designs. The process flows of some commercial products are described in detail. Design trade-offs such as monolithic integration versus hybrid and single-axis versus three-axis are discussed. Packaging issues and future trends are also addressed.