A mean field‐crystal field theory is developed for random, multi‐component, anisotropic magnetic alloys. It is specially applicable to rare earth alloys. A discussion is given of multicritical points and phase transitions between various states characterized by order parameters with different spatial directions or different ordering wave vectors. Theoretical predictions for the phase diagrams and magnetic moments, based on known parameters for the rare earth alloys Nd‐Pr, pure dhcp Nd, TbEr and TbTm alloys, agree with experimental observations. A simple procedure to include fluctuation corrections in the mean field results is also discussed.