Electron polarimeters based on Mott scattering are extensively used in atomic and molecular, solid state, nuclear, and high‐energy physics. This use stems from the increasing realization that much additional information concerning many physical processes can be obtained through spin‐dependent measurements. In this review we discuss the basic physics and application of Mott polarimetry. A number of different Mott polarimeter designs are described that illustrate the wide range of operating energies (10 eV–1 MeV) and geometries that can be used in such instruments. The calibration of Mott polarimeters is discussed together with the potential sources of systematic error that can arise and that can limit measurement accuracies. The aim is to present a comprehensive practical guide to Mott polarimetry and the capabilities of the technique.