A window cornice assembly is disclosed. The window cornice assembly may comprise a front section and two side sections upon which fabric may be arranged. Corner pieces may be mounted on the front and side sections. Fabric may be arranged and secured on the front and/or side sections by clips that retain the fabric taut and over the front face thereof. The clips can be attached to each other directly by an elastic cord or band, or attached to the rear face of the front section directly so that the fabric is tightly pulled over the front face of the front section. The elastic cord or band imparts a desired amount of elasticity to the fabric. The window cornice assembly may have one or more elongated channel-shaped support strips arranged on a front section to provide additional rigidity thereto.