Data from the Thai Demographic and Health Survey, conducted in 1987, confirm evidence from earlier surveys that the decline in the duration of breastfeeding evident during the 1970s came largely to a standstill in the 1980s. In addition, the proportion initiating breastfeeding, while high throughout the period, has increased to the point where, at the national level, it is now close to universal. These changes coincide with efforts, primarily undertaken or coordinated by the Ministry of Public Health, to promote breastfeeding and discourage use of breast milk substitutes. While substantial socioeconomic differentials in the duration of breastfeeding exist, initiation is common even among the groups that breastfeed for the shortest period of time. Breastfed children are generally given supplemental foods or liquids at very early ages. It is common to breastfeed children relatively frequently during the day and evening. Bottles with nipples are used to provide supplementary food to breastfed children by a substantial proportion of mothers. Most use of bottles with breastfed children is not for the provision of infant formula but for other types of supplemental food.