A suspended ceiling system in one embodiment includes a grid support member and a ceiling panel supported on the member. A resiliently compressible gasket is disposed at the interface between the grid support member and peripheral edge of the panel. The gasket may be fixedly attached to the panel peripheral edge in the factory under controlled conditions before shipment to the ceiling installation site. In one embodiment, the gasket may be adhesively attached to the panel. Mounting the ceiling panel on the grid support member compresses the gasket to preferably form a minimally visible air leakage resistant seal between the air plenum space above the ceiling panels and the occupied space below. This retards air exchange between the spaces which enhances heating/cooling efficiency, noise reduction and allows formation of pressurized clean rooms.