Abstract: An underground automatic parking system has a vertical well with two spaced elongated vertical side compartments each having a plurality of parking spaces. An elevator with a car transfer mechanism is located between the compartments. A plurality of slides are arranged in the parking spaces. Each slide has two side headers of triangular form and a rectangular frame which supports a corresponding plurality of vehicle carrying platforms. The slides are horizontally displaceable on tracks arranged along the ends of each parking space of the well between a retracted position within one of the side compartments and an extended position to intersect the path of the transfer mechanism on the elevator.