Abstract: A U-shaped corner clip for use with mitered corners of first and second hollow frame members. One leg of the clip has a hook to engage an opening in the outer edge of a first frame member. The other leg is insertable through an opening in the second frame member but has a length such that it passes from the interior of the second frame member into the interior of the first frame member and there resiliently bears on the inner face of the inner edge of the other frame member. Thus, any force tending to rotate the frame members apart in a direction to increase the angle therebetween is resisted by the action of the second leg member on the first frame member. The clip also resists any force tending to move the frame members linerally away from each other in any direction.