Toner compositions have a post-blended particulate additive which comprises aluminum oxide and aluminum hydroxide with, optionally, a third component such as silica or a wax, which is a tribo-charging additive which, upon tribo-charging of the toner particles, shifts the charge distribution in either the positive or negative direction. As well as providing toner compositions having adequate fluidity, the use of pre-extrusion charge-control additives can be avoided. There are also advantages, for example, in terms of charge distribution characteristics, stability of charge distribution, and avoidance of matting effects. Developer compositions are formed by admixture with suitable carrier particles.