An adapter for attaching an accessory, such as a light, to a partition frame is disclosed. In one form, the adapter includes two opposed brackets. Each bracket has a base, a side wall extending downwardly from the base, a flange extending inwardly from the side wall, and a wall extending upwardly from the base. The brackets may be installed to the partition frame by inserting the flange of each bracket in a slot in the side of the partition frame. When the brackets are installed to the partition frame, a post structure including the upright walls is formed. The post structure is used for attaching the accessory. In another form, the adapter includes a post and a support member. The support member may mounted to the partition frame or to a mounting bracket attached to the partition frame. The post may be used for attaching the accessory.