Replacement of delivery settlement of futures contracts with cash settlement is frequently proposed to reduce the frequency of market manipulation. This article shows that it is always possible to design a delivery-settled futures contract that is less susceptible to cornering by a large long than any given cash-settled contract. Such a contract is more susceptible to manipulation by large shorts, however. Therefore, cash settlement does not uniformly dominate delivery settlement as a means of reducing the frequency of market power manipulations in derivatives markets. The efficient choice of settlement mechanism depends on whether supply and demand conditions favor short or long manipulations. Copyright 2001 by University of Chicago Press.