Abstract: A computer mouse accessory includes a platform having a substantially planar upper surface upon which a computer mouse can be operated, a bracket for mounting the accessory to a support structure, such as keyboard shelf, the platform being secured to the bracket in a manner which allows for linear movement of the platform with respect to the bracket along a generally horizontal line. The linear adjustability of the platform relative to the bracket allows the platform to be positioned anywhere between a fully deployed position wherein the platform is located laterally adjacent to an end of a computer keyboard shelf to which the bracket is secured, and a fully retracted position wherein the platform overlies one side of the keyboard so that when the keyboard shelf is mounted on an articulated arm secured to the underside of a worksurface of the desk, the keyboard shelf and computer mouse accessory can be store together beneath the worksurface.