This Recommended Practice (RP) provides guidelines for selecting accelerometers to measure shock and vibration in laboratory and field testing environments. There are basically two classes of motion sensors: fixed-reference and mass-spring (relative motion). This RP concentrates on the more common mass-spring type accelerometers, with the sensing element(s) represented by the spring. Recommendations are made in terms of performance characteristics rather than instrument construction, brand, or model number. Various sensing technologies are discussed in detail to provide a good understanding of design trade-offs.