According to Rawls, the worst-off subgroup of the population should be identified by its low endowment of “primary goods”. Since primary goods are multi-dimensional, he proposed constructing a synthetic index. But there seems to be a dilemma with respect to such an index. Either it is unique, and then individual preferences about the various primary goods are disregarded, while the index reflects a perfectionist view of the good life. Or it respects individual preferences, but in that case Rawls’ theory seems to fall prey to the classical problems of welfarism. This paper shows that the synthetic index of primary goods can respect individual preferences without being merely a measure of subjective utility. The precise form of the index depends on ethical principles about how to share resources. In addition, this approach offers a new justifica