Improved electrographic development is obtained in the presence of a development electrode field by predeterminedly rotating both the core and shell of a magnetic brush applicator to supply developer, of the kind comprising small particle, hard-magnetic carrier and electrically insulative toner, to an electrostatic imaging member which moves past a development station with predetermined linear velocity. In one preferred embodiment the core and shell are predeterminedly rotated so that the shell moves through the development zone at a rate preventing toner that is plated-out on the shell from affecting image development and so that the developer moves co-currently with the imaging member at a generally equal linear velocity.