This woman is elegantly dressed, and admiring herself in a mirror on the wall. She is at the right, the mirror at the left, and the real subject of the painting is the light-filled space between them. She is caught in spontaneous action, just at the moment when the yellow ribbons are taut; she is in her dressing-room, wondering if she is wearing the right jewelry. On the table in front of her is a brush for face-powder, a comb, a silver box, and a large Chinese jar. There is also a small note -- could this be a letter from her lover, for whom she is dressing?
The mirror seems to be too high for the woman to see her reflection; this may be a sacrifice to composition. The painting is divided diagonally into light and dark, with the mirror and window forming one vertex of the light triangle, and the woman forming the opposite side. At the top and right side of the painting, and at the bottom at the chair seat, there is damage because the canvas was once smaller. Vermeer may have recognized that the composition would be stronger by eliminating the extra space to concentrate attention on the wall between the woman and the mirror.