The insufficient attention that too often is paid to the characteristics required of attribute weights prevents multiattribute decision rules from accurately representing preferences. The weighting summation or linear model requires weights to be proportional to the relative value of unit changes in their attribute value functions. Only then will weights accurately reflect the trade-offs decision makers are willing to make.A number of methods of choosing weights are critiqued from this perspective. Applications of weighting methods in power plant siting are surveyed, and a siting study of western Maryland is presented. Two weighting methods were used, one deriving weights from trade-offs made by decision makers and the other asking decision makers to choose weights on a scale of 0 to 10. The locations picked by the two methods differ strikingly.