111 primiparous women who had chosen to breast-feed their normal healthy term infants were assigned to one of four groups matched for age and social class. Two groups had the baby put to the breast within 10 min of delivery and the other two began breast-feeding 4--6 h after delivery. One of each pair of groups fed 2-hourly and the other 4-hourly. Follow-up over 18 months suggested that both early initiation and increased frequency of breast-feeding extended the nursing period, the former having the greater effect. 2-hourly feeding induced lactation at least 24 h earlier than did 4-hourly feeding.