Abstract: A supplementary cap, or mounting bracket, is provided for one or both ends of the head rail of a venetian blind. The mounting bracket or brackets must fit snugly, but slideably over the ends of the head rails of the venetian blind, and be strong enough to support the venetian blind when they are secured against the insides of the window frame jambs. Each mounting bracket includes a lever arm that can be turned to rotate a cam, within the bracket, that will urge a spacer against the adjacent end of the head rail and force the outer end of the mounting bracket against the inside of the adjacent window frame jamb. By selecting an appropriate length of head rail, mounting brackets, and spacers, the venetian blind unit should fit between the insides of the window frame jambs, and turning the lever arms will force the ends of the mounting brackets against the jambs to support the venetian blind, without screws or fasteners, securely, but removably, for adjusting or cleaning.