A modular lighting system features a universal mounting method for lighting elements, such as LED lights, as well as various electrical devices, and is configurable in multiple modes of operation. In one aspect, LED strips are inserted into slots in the lower surface of the rail member. Another aspect allows operation with tube lamps, such LED tube lamps. In still another mode of operation, discrete electrical or electromechanical components may be employed, powered by electrical power available in the rail. In yet another more, an up and down, bidirectional lighting system is provided.