Providing technical means to detect, prevent, and reverse the threat of potential illicit use of radiological or nuclear materials is among the greatest challenges facing contemporary science and technology. In this short article, we provide a brief description and overview of the State‐of‐the‐art in sensor development for the detection of radioactive materials, as well as an identification of the technical needs and challenges faced by the detection community. We begin with a discussion on γ ray and neutron detectors and spectrometers, followed by a description of imaging sensors, active interrogation, and radiation detection materials' development, before closing with a brief discussion on the unique challenges posed in fielding sensor systems.