A diaphragm-type, strain-gage, surface-slope sensor has been designed for off-road vehicles. The sensor is capable of continuously measuring surface slopes in longitudinal and lateral directions simultaneously. Instrumentation amplifiers with low-pass filters were used for signal processing. Laboratory tests showed that the sensor had satisfactory sensitivity, linearity, and dynamic characteristics. Potential applications of the slope sensor include studies of vehicle mobility, stability, tractive performance, and safety.