This paper presents two high performance wide sensing range MEMS accelerometers, built using different techniques. The paper comprises two sections. In the first section, open-loop accelerometers with up to 40 g sensing range and 18 bit dynamic range are presented. In addition to a discussion on design, statistically based test results are demonstrated. In the second section, a closed-loop sigma-delta accelerometer with 30 g sensing range and 21 bit dynamic range is presented, including a short design review and test results from the most recently fabricated batches. Our open-loop accelerometers have demonstrated tactical grade performance featuring 0.5 ppm of full range/√Hz noise, 100 ppm bias stability, and 0.5 % of full range nonlinearity. Our closed-loop accelerometer, designed to compete with traditional macro electro-mechanical quartz accelerometers, features <;10 μg bias instability, 0.1% typical nonlinearity over full 30 g sensing range, and less than 100 μg/g_rms² Vibration Rectification Error (VRE) up to a 2 kHz frequency range. Both open-loop and closed-loop sensors represent a fully integrated system comprising a uniquely designed MEMS device enclosed in a specially built LCC package with a proprietary ASIC.