An adjustable drapery form structure provides form to the header portion of a drapery panel. The structure has a platform and a form member capable of surrounding an end of the platform. A track, with discrete stops along it, is oriented perpendicularly to that end of the platform. A hanger member that attaches to a drapery rod can be selectively adjusted between track stops. Trimming notches at an end of the form member may be removed to provide additional adjustability to the structure.