A method and system for stimulating tissue using a plurality of electrodes is provided. Desired electrical parameter (e.g., field potential) values are determined at a plurality of spatial points. A plurality of constituent current sources is selected at the locations of the electrodes. The relative strengths of the constituent current sources that, when combined, result in estimated electrical parameter (e.g., field potential)|values at the spatial points that best matches the desired electrical parameter values at the spatial points are determined. The polarity and percentage of electrical current to be associated with each of the electrodes is selected based on the determined strengths of the constituent current sources. Electrical current is conveyed through the plurality of electrodes in accordance with the selected electrical current magnitudes to stimulate the tissue.