In this paper we develope a model to analyze the electrostatic waves produced in the shock foot at Jupiter. We show that that an ion beam instability involving the ions reflected at the shock ramp and the incoming solar wind electrons produces waves at the observed frequencies and that saturation via orbit diffusion limits the waves to amplitudes near to what is observed. Results from two-dimensional model of the reflected beam in the foot indicates that the waves propagate against the solar wind away from the shock ramp and are amplified up to their saturation amplitudes. The saturation results combined with the electron temperature profile due to wave-particle interactions predicted by quasi-linear theory reporduce a wave amplitude profile for the shock foot that is in reasonable agreement with the observations. ¿ American Geophysical Union 1988