Abstract: An insulated window shade assembly includes a pleated, two-ply window shade and two cooperable guide rails which are adapted for attachment to the side walls of a window casing. The shade consists of two pleated plys, which in the preferred embodiment are interconnected by means of draw strings which pass through the pleats. The edges of the pleated plys are shaped so that the unfolding of the pleats as the shade is lowered results in the edges forming an air-tight seal with the guide rails when the shade is fully lowered. As the shade is raised the edges of the pleated plys partially draw away from the guide rails to as to facilitate raising and lowering of the shade.