Over the last five years a family of cobalt‐rare earth permanent magnet alloys has evolved, of which Co–Sm and Co–Pr–Sm have the highest permanent magnet properties. A remarkable improvement of properties has been achieved in a relatively short period of time, for example the (BH)max energy product has increased by a factor of five, the B‐coercive force by a factor of three, and the remanent magnetization Br by a factor of two. These improvements in properties have resulted from improved processing techniques producing high density magnets with a high degree of alignment without loss of coercivity. In this review, the influence of various processing parameters; such as alloy composition, particle alignment, sintering density, and post sintering heat treatment; on saturation, remanent magnetization, and coercive force are discussed. Improvements in these magnetic properties achieved by careful control of processing will be stressed. In addition, a summary of the properties of the more promising Co–R alloys is given.