Studies of prehistoric patterns of health and disease focus on interpretations of the evidence from hard tissue remains of past peoples. These interpretations are based on observations of living peoples and the sources of stress which may be expected to leave a record in their bones and teeth. One presumed source of stress that has received wide attention in the recent literature is weaning. The process of weaning is often associated with elevated risks of infant mortality and morbidity because infants no longer receive passive immunity from their mothers, and they are exposed to new sources of infection through the weaning diet. The process of weaning has also been tied to the duration of the contraceptive effects of nursing and the return of fecundity, which in turn provides information about birth spacing and population growth. Recently some of the basic assumptions about nursing and weaning, and their effects on morbidity, mortality and population growth, have been challenged, based on new technical and cross-cultural information. It is clear from the demographic literature that some studies based on skeletal samples tend to be too simplistic in terms of the causes of infant morbidity and mortality. This paper reviews current research which relates weaning and infant mortality to health and reproduction in past populations and evaluates studies of enamel hypoplasia and bone chemistry for reconstructing infant feeding practices in the past. © 1996 Wiley-Liss, Inc.