Planetary auroral emissions are an observable signature of the coupling between the planetary magnetosphere and ionosphere. Jovian and Saturnian auroral emissions are created by a variety of processes, including those driven by the orbital motions of moons through the planetary magnetic plasma, the local creation, and subsequent pickup of plasma in the inner magnetosphere, due to the geologically active moons Io and Enceladus, respectively, and the radial transport of plasma through the middle and outer magnetosphere. Along with these internally driven phenomena, there exist auroral emissions owing to the global interaction of the planetary magnetosphere such as the release of plasma down the magnetotail. The current understanding of Jovian and Saturnian auroral processes is derived from attempting to reconcile theoretical models of ionosphere-magnetosphere coupling with physical parameters derived from auroral observations and in situ magnetospheric data. We focus on the processes limiting the strength of the ionospheremagnetosphere coupling that predominantly occur in the ionosphere and at high latitudes along the magnetic field line.