This chapter gives a brief introduction to shock response spectra and is intended to be a primer for the analysis of structures subject to shock loads. The shock response spectrum is a graphical representation of an arbitrary transient acceleration input, such as shock in terms of how a single-degree-of-freedom system (like a mass on a spring) responds to that input. A mechanical or physical shock can result from impact, drop, explosions, earthquakes, large electrical discharges, etc. A shock response spectrum transforms the acceleration time history from the time domain to the maximum response of a single-degree-of-freedom system in the frequency domain. The assessment of such disturbances is extensively discussed in numerous existing texts and therefore only touched on herein. The focus is on simplified models for single- and multiple-degree-of-freedom systems. Discussion of random loading and the basics of input–output relations are presented.