Until about 30 years ago breast-feeding was the natural and common method of infant feeding. With increasing technical possibilities in food industry, transfer of birth into hospital and displacement of female activities outside the family, the frequency of breast-feeding decreased, being replaced by artificial feeding methods. This work treats the impact of the two feeding methods (breast and bottle feeding) on the psychomotor and social development of the baby in the first year of life. The theoretical part gives a review of the mother-child interaction and the psychomotor and social development. As hypotheses have been proposed the suppositions that breast-feeding in the first three months of life leads to essential developmental advances in psychomotor and, above all, social maturity. This is due to the intensive visual and olfactorial experience and perception, the advantages of nutrients in breast-milk and, last not least, to the infant's autonomy regarding food quantity and time intervals. The quality of mother-child interaction is essentially influenced by the feeding method, because distance and proximity have an essential influence on their relation. As an important sign of intellectual maturity was regarded to fear reaction to strangers. The empirical part examines the hypotheses by comparing the development of breast-fed and bottle-fed babies. The psychomotor and social development of breast-fed babies clearly differs from that of bottle-fed ones and leads at the age of 12 months to significant developmental advantages of the psychomotor and social capabilities. Some suggestions are given to ensure mental health in the first year of life.