Abstract: A self-aligning curb box assembly is provided. The curb box includes a cylindrical conduit extending from the ground surface downwardly and has a detachable cover at its upper, surface end. The conduit has an inverted “U” shaped passageway formed at its lower end through which a generally horizontally oriented supply line, such as for water or gas, passes. The supply line has a valve body and an “open-to-shut” valve cock located in the line positioned within the passageway at the lower end of the curb box, the valve cock extending upwardly. The assembly includes a positioning insert placed within the curb box at its lower end thereof. The insert limits lateral movement of the valve body in any direction throughout 360° in the plane about the valve when the insert is installed.