The basis of near-infrared spectroscopy (NIRS) is founded on light reflection and absorption through tissue and specific molecular chromophores. By using multiple wavelengths of light, chosen to leverage the specific light absorption properties of oxyhemoglobin and deoxyhemoglobin, it is possible to estimate relative concentrations of these 2 molecules in tissue. Compartment syndrome occurs when the pressure within a closed fascial space precludes delivery of oxygen to the affected extremity. Thus, NIRS presents a unique opportunity for noninvasive monitoring of muscle oxygenation saturation. This article presents an overview of NIRS technology and its evolution over the past 2 decades, a review of the current literature investigating the use of NIRS in both acute and chronic exertional compartment syndrome, and guidance for anatomic sensor placement.