Many railroads are installing new Communications Based Train Control (CBTC) systems and replacing their relay based signaling equipment with solid state equivalents. When installing new signaling and train control equipment on a property, laboratory Electromagnetic Compatibility (EMC) testing is an important part of the qualification process. Much of the new train control equipment is designed and manufactured overseas and Commercial Off The Shelf (COTS) equipment is frequently incorporated into subsystem designs. It is, therefore, important that the railroads and system providers understand the railroad EMC requirements, and that the equipment being installed is tested to the appropriate standards in the laboratory in order to ensure that it will operate as intended in the field. The two main equipment level laboratory qualification testing standards referenced in railway signaling contract specifications are the Military Standard MIL STD-461F and the CENELEC (European Committee For Electrotechnical Standardization) Standard EN 50121 (IEC equivalent IEC 62236). Although the two standards are similar, there are some key differences that can lead to costly delays if not properly understood and addressed. This paper will provide a comparison of these two standards, including the different test methodologies, specific test procedures, and test limits.