Uncertainties of targeted emission control strategies aimed at the cost-effective control of sulfur deposition in Europe are evaluated using two procedures. The first accounts for parameter and data errors using a chance-constraint procedure. The second examines the effect of interannual meteorologic variability. Several techniques increase the accuracy and speed of the computations. Uncertainties are determined for scenarios using single, regional, and European-wide targets. For single and regional deposition targets, uncertainty decreases the specificity of prescriptive emission reductions and requires additional emission abatements. Cost and removal minimizing strategies have large differences. Providing a margin of safety is expensive for some deposition targets.