In the Earth's atmosphere, a zonal flow oscillation is observed with periods between 20 and 32 months, the Quasi Biennial Oscillation. This oscillation does not require an external time dependent source but is maintained by nonlinear wave momentum forcing. We propose that such a mechanism also drives long-period oscillations in planetary and stellar interiors, and we apply it here to generate a flow oscillation for the 22-year solar cycle. The oscillation would occur just below the convective envelope-in a region where gravity waves can propagate. We present results from a simplified analytical model that incorporates Hines' gravity wave parameterization. Wave amplitudes <10 m/s can produce reversing zonal flows of 20 m/s that should be sufficient to generate a corresponding oscillation in the poloidal magnetic field. The low buoyancy frequency and associated increase in turbulence help produce the desired oscillation period of the flow and should help generate the currents for the reversing magnetic field. ¿ 2001 American Geophysical Union