Several micro-scale nanopositioning mechanisms, or MEMS nanopositioners, have been developed for application in nanotechnology and optical sensors. In this paper, the design and modeling of these devices is presented along with initial experimental results. The MEMS nanopositioner is comprised of a parallel bi-lever flexure mechanism and a bent-beam thermal actuator. The flexure mechanism is designed to amplify and guide the motion of the actuator with high precision, while the thermal actuator provides the necessary force and displacement. The relationship between the applied voltage and resulting displacement for this mechanism has been calibrated using a scanning electron microscope and a simple image processing technique. A finite difference thermal model along with a FEA representation of the flexure mechanism and actuator is used to estimate the motion range of the device. Results from this method are compared with experimental calibrations, showing that the model provides a sufficient approach to predict the mechanism’s static performance. Finally, an open-loop controller based on calibration data was used to demonstrate the nanopositioning capabilities of these devices. The motion repeatability was found to be less than +/- 7 nm and step sizes well below 50 nm are possible, indicating suitable performance for many nanopositioning applications.