This valuable collection of essays presents and evaluates techniques of body-mass estimation and reviews current and potential applications of body-size estimates in paleobiology. Papers discuss explicitly the errors and biases of various regression techniques and predictor variables, and the identification of functionally similar groups of species for improving the accuracy of estimates. At the same time other chapters review and discuss the physiological, ecological, and behavioral correlates of body size in extant mammals; the significance of body-mass distributions in mammalian faunas; and the ecology and evolution of body size in particular paleofaunas. Coverage is particularly detailed for carnivores, primates, and ungulates, but information is also presented on marsupials, rodents, and proboscideans.