Information on infant feeding and child development was obtained from the 1970 British Births Survey and subsequent follow-ups at five and 10 years of age. A clinically advantaged subsample of infants who were either exclusively bottle-fed or exclusively breast-fed for at least three months were selected in order to minimise biases against a disadvantaged bottle-fed group. Only in the area of educational ability and attainment were differences observed as a function of the child's feeding patterns as an infant. Higher vocabulary test scores at five years and higher British Ability Scales test scores at 10 years were significantly associated with exclusive breast-feeding for more than three months. These data support and extend results obtained in previous studies on long-term developmental differences between breast-fed and bottle-fed children.