This paper presents research at The University of Michigan on micromachined capacitive silicon accelerometers and gyroscopes with their interface electronics to satisfy the requirements for inertial navigation applications. The accelerometer systems developed employ in-plane (lateral), out-of-plane (z-axis), and single-chip 3-axis sensors with the interface electronics. The interface electronics forms a second-order electromechanical sigma-delta modulator together with the sensor and the system can be operated in both open and closed-loop. These devices can achieve better than 2mug/rootHz resolution with a range of +/-1.35g. The single-crystal silicon ring gyroscope provides 132 mV/deg/sec sensitivity and 10 deg/hour resolution.