The electromagnetic susceptibility of electronic devices varies substantially from one device to another. The objective of the following study is to better understand the statistical variation in coupling to printed circuit boards (PCBs) and their attached cables, and thus their susceptibility. Models are being developed to estimate coupling to wiring harnesses and PCB traces. The voltage coupled depends on the frequency, angle of arrival, and polarization of the incident wave, as well as the characteristics of the receiving structure. The statistical characteristics of the coupled voltage with variations in the arrival angle, polarization and typical variations in the receiving structure (e.g. length of wiring harness, size of connector, board size, trace location, etc.) are being found through simulations. These variations in coupling were used to predict the frequency content of the incident wave that is most likely to cause an over voltage or current within the studied parameter space. Existing models explore differential mode coupling to traces and common-mode coupling to harnesses. Differential mode models of the harness and connectors are under development. These and the previous modeling blocks ultimately create a 'toolbox' with which estimate the statistical variation in coupling to a variety of devices.