This paper is concerned with a novel problem in the field of parametric vibration whereby a single-degree-of-freedom oscillator is coupled to a power take-off mechanism so that the response of the oscillator in principal parametric resonance is directed towards doing work on an external body. The results show that it is possible for such an oscillator to transmit a certain amount of power from a vibrational source to a sink, in this case a weight which is lifted vertically. The existence of a steady state response of this nature shows that the imposition of an external load cannot be considered merely as a remote damping effect, and that oscillatory motion of the system can be maintained throughout provided the inherent damping within the system is minimized and that the necessary 2:1 relationship between the exciting frequency and the natural frequency of the oscillator is reasonably well maintained. Clearly, the external load also dictates the required threshold of excitation acceleration magnitude for the system to respond steadily. Considerable analytical, numerical, and experimental work has been carried out to substantiate the ideas proposed within the paper.