Abstract Microelectromechanical systems (MEMS) that sense, think, and act are enabling technologies currently employed in many industrial applications. To operate these devices, a stimulus is required to produce motion. In MEMS, this stimulus may be thermal actuation using current to produce joule heating, or electrostatic actuation using voltages to create electric fields. To qualify MEMS technology, these devices must undergo repeated characterization and testing and at both the die and system level. Electrical overstress (EOS) and electrostatic discharge (ESD) are two important tests used to assess the robustness of a device to steady state and sharp voltage and current transients. Identifying the failure mechanism and understanding the root causes for failure is paramount to the overall improvement and success of any MEMS based system. In this paper we will focus on the effects of EOS and ESD events on surface micromachined polysilicon based electrothermal actuators fabricated using the SUMMiT V™ process.