Abstract: A very thin and rugged illuminated sign has a transparent, light-source plate with cavities in its edges to receive light bulbs. One side of the plate is covered with opaque material and the other with translucent material. Both surfaces are internally reflective, so that light from the bulbs is conserved and distributed substantially uniformly throughout the plate. At least one opaque plate, having a transparent (preferably colored and embossed) character therein, covers the translucent side of the light-source plate; so that light therefrom illuminates the characters. The terminal ends of the light bulbs are oriented outwardly for easy connection in an electric circuit concealed in a frame that surrounds both plates and confines them together. The frame may function as one of the electrical conductors.