Behaviours of seven Japanese mother-infant dyads during daytime feeding of both milk and solids were observed longitudinally to the middle of the second year. The first 3 months were a period of exclusive milk-feeding largely uninterrupted by mother-infant social interaction. In the following 6 months there was increasing mother-infant communicative interaction during milk-feeding and the mother began attempts to feed solids. After 8 months, weaning was promoted by reduction in some types of interaction during milk-feeding, and increased rejection by the infant of passive feeding as self-feeding of solids increased. Self-feeding was at first mainly by hand, and later with tools. A positive correlation was found between hand-feeding at 12-14 months and active physical stimulation of the infant by the mother during milk-feeding in the first year. Self-feeding of solids with tools increased significantly after 1% years, and the mother supported this development. The mother showed non-intentional eating-like mouth movement at the moment infants ate (empathetic behaviour), and this behaviour peaked in the latter half of the first year and decreased thereafter. The development of independence or autonomy in feeding was a mutual or cooperative process between mother and infant, and was initiated by the infant rather than imposed by the mother.Key words: Weaning, milk-feeding, solid-feeding, empathetic behaviour, rejection, autonomy.Mammalian offspring are at first nutritionally dependent on their mother's milk. According to a sociobiological hypothesis, weaning is the process of reducing this dependency, and hence reducing the mother's 'biological burden'. This would suggest that it is she who takes the initiative.*Address for correspondence: Koichi Negayama, Food Science Department, Mukogawa Women's University, 6-46 Ikebiraki, Nishinomiya, Hyogo 663, Japan Thus Trivers (1974) concluded that disagreement on the time of weaning between mothers and offspring causes conflict. The source of nutrition for young mammals normally begins with breast milk then solids are introduced, and the process of weaning is most simply described as a shift between the two kinds of food, one produced by the mother and the other not. Altmann (1980) explained weaning of baboon offspring as a consequence of conflict between the offspring's nutritional demand and the mother's capacity to fulfil it.