Thermal imaging allows officers to see in low light to no light conditions. However, the high cost and general lack of knowledge regarding thermal imagining have limited this technology’s use in law enforcement. Today, thermal imagers are available for a fraction of what they cost a decade ago and their new designs are smaller and lighter. The Law Enforcement Thermographers’ Association (LETA) has approved 11 law enforcement uses for thermal imagining: search and rescue, fugitive searches, vehicle pursuits, flight safety, marine and ground surveillance, perimeter surveillance, structure profiles, disturbed surface scenario, environmental law enforcement, officer safety, and hidden compartments in vehicles. The use of thermal imaging in each of the 11 circumstances is described in turn. Next, the author describes how thermal imagers work by sensing the infrared energy emitted by objects to generate real-time images of the scene. The differences between the two classifications of infrared detectors, photon detectors and thermal detectors, are discussed. While photon detectors are more sensitive than thermal detectors, they require cryogenic cooling to obtain the maximum sensitivity; thermal detectors provide optimum performance at room temperature making them more convenient for field use. Next, differences are enumerated between the two major categories of current night vision technology, image intensification and thermal imaging. From a tactical perspective, thermal imagers are the better night vision choice because they allow officers to perform their duties with greater efficiency and safety. The major factor limiting the widespread use of thermal imagers continues to be its price.