A mechanism for producing quasi-periodic fluctuations in the intensity of auroral light is proposed in which pressure waves in the neutral atmosphere drive the pulsations. A model is constructed to describe how a horizontal movement of the atmosphere can cause the energy deposition by a steady particle distribution to vary with time if the isodensity surfaces of the local atmosphere become nonplanar. When the distortions are wavelike corrugations and the horizontal motion is steady and also has a component normal to the phase front, periodic variations in auroral brightness can result. The pulse shape and the magnitude of the pulsations depend on both the energy spectrum and the pitch angle distribution of the particles and the amplitude and altitude distribution of the atmospheric waves. It is suggested that the required atmospheric oscillations can be provided by acoustic-gravity waves which are generated by active arcs near the poleward edge of the auroral oval. This mechanism can also produce aperiodic pulsations by convection of irregular atmospheric density fluctuations, some of which may result from interfering acoustic-gravity wave trains.