A plug-in lamp assembly for use as a picture element in an information display screen includes a plurality of low-pressure arc discharge lamps for selectively generating multiple colors, a lamp plug for interconnection and mounting of the discharge lamps, and a lamp socket for plug-in attachment of the lamp plug. Each discharge lamp has electrical leads extending from a first end thereof and a light output region at a second end thereof. The lamp plug comprises a base having spaced-apart electrical connector pins and a cap attached to the base. The first ends of the discharge lamps extend through openings in the top wall of the cap into the lamp plug, and selected electrical leads are coupled to the electrical connector pins. The lamp plug and the lamp socket include openings for directing cooling air over the first ends of the discharge lamps. The cooling air is preferably directed from the rear of the display screen through the lamp socket and the lamp plug and is exhausted through the front of the display screen. The lamp socket preferably includes an upstanding locating projection and a spring clip for retaining the lamp plug.