Inertial sensors such as accelerometers and gyroscopes have been widely used since the early 1990s to monitor the condition of transportation assets. Recent improvements in their performance, a reduction in cost, and sensor miniaturization has resulted in a growing interest expanding their use. This research is an extensive and systematic review of their application considerations, challenges, and opportunities for improvements in railroad track condition monitoring. Research questions were developed to guide the selection of relevant articles from databases. The authors report key findings in the areas of sensor specification, sensor location, and sensor signal processing.