Substantial variations in landowner's share under sharecropping arrangements are documented. Partial relationships between landowner's share and land quality and between landowner's share and physiological population density are explained by extensions of the competitive theory of share tenancy. It is shown that high landowner's share can be expected to be associated with high land quality and or high physiological density. The tendency for increases in population to be associated with increases in landlords' shares can be ameliorated by land-saving technological change.