In this work, we present a theoretical and experimental investigation into the effect of the motion of a printed circuit board (PCB) on the response of MEMS devices to shock loading. For the theoretical part, a two-degrees- of-freedom model is used, where the first-degree-of-freedom accounts for the PCB. The second-degree-of- freedom represents the motion of the MEMS microstructure, such as a beam or a plate. Acceleration pulses are applied to the MEMS-PCB assembly base (such as those generated from a drop table test). Simulation data are presented to show the effects of the natural frequency of the PCB, the natural frequency of the microstructure, and the shock pulse duration. Universal 3-D spectra representing the effect of these parameters are presented. These spectra can help MEMS designers ensure safe operation of their MEMS devices. It is found that neglecting the PCB effect on the design of MEMS devices under shock loads can lead to undesirable motion of their microstructures. An experimental investigation is conducted to verify the theoretical results using a capacitive accelerometer. Experimental data for the response of the accelerometer while it is mounted on two representative PCBs due to different base shock load conditions are shown. It is found that these data are in good agreement with the simulation results.