In a method for joining a thread a spindle rotor with hollow spindle shaft is rotatably supported on a machine frame. A radially outwardly extending yarn guide channel is connected to the hollow spindle shaft. Two spinning devices with upwardly open spinning rotors are supported above the spindle rotor symmetrical to the central axis of the spindle rotor. A centering point is positioned on an extension of the central axis of the spindle rotor. A spun yarn is spun in each spinning device from dissolved fiber material and led upwardly away from the spinning rotors, reversed in their direction of movement by 180.degree., and introduced into the hollow spindle axle. The spun yarns form a yarn balloon between the yarn guide channel and the centering point, and twisted yarn is removed from the centering point. The dissolved fiber material is fed to the spinning devices through the yarn balloon. For each spinning rotor a joining thread is threaded with one end into the hollow spindle axle and with the other into the spinning rotor. A thread loop is generated from each joining thread between the and guided such that a first thread branch is fed into the spinning rotor and the second thread branch is removed through the hollow spindle axle until the thread loop is resolved, the direction of movement of the first thread branch is reversed, and the joining thread is removed through the hollow spindle axle.