A ceiling panel according to the present invention has opposed translucent membranes secured in a tensioned state across a perimeter frame. The frame includes frame members that are designed to oppose inward bowing of the perimeter frame caused by the tensioned membranes. The frame members have a side profile shaped to conceal a grid support network with the lower translucent member extending across and about a lower edge of the perimeter frame. The invention also includes a modified structure for supporting of translucent panels below a grid network.