Two ways are examined in which particle precipitation can affect the overall pattern of magnetospheric convection. First, loss due to precipitation may reduce the effectiveness of the shielding process that acts to prevent the high-latitude convection electric field from penetrating to low latitudes. Second, electron precipitation can strongly influence the flow pattern by modifying the ionospheric conductivity. We conclude that shielding by the plasma sheet electron boundary is likely to be strongly dependent on the loss rate, but at the inner edge of the proton ring current it will always have some importance. We also find that the combined effect of shielding and enhanced conductivity in the auroral zone can be rapid flow in the ionospheric trough, similar to recent observations.