Abstract: A portable stage has supporting structure extending lengthwise of a trailer dimensioned for highway travel and provided with a central turntable and tracks leading therefrom to both ends of the trailer. Each of a series of joists has a carriage and the turntable is dimensioned to enable all the carriage to be stored thereon side by side. In a first position of the turntable, the joists extend lengthwise of the trailer and in a second position, the joists extend transversely thereof and the carriage is thus positioned to travel along the tracks and be spaced therealong to enable floor members to be detachably attached thereto.