A significant increase occurred in the initiation and duration of breast-feeding among Honduran women between 1981 and 1987. Changes in population characteristics (e.g. level of education of women) would be expected to lead to a decrease in breast-feeding at each infant age, but these were offset by behavioural changes that led to an increase in the likelihood of initiation and continuation of breast-feeding. An exploration of relevant factors suggests that the PROALMA breast-feeding promotion programme has had a profound effect on the breast-feeding behaviour of Honduran mothers.