Breast-feeding makes a unique, fundamental contribution to the health and nutrition of infants. The World Health Organization International Code of Marketing of Breastmilk Substitutes is designed to encourage, promote, and protect breast-feeding in all WHO member states. The Code acknowledges that a number of social and economic factors affect the decisions of women to breast-feed and that breast-feeding has declined. Member states have been urged, therefore, to develop appropriate social support systems to overcome and adjust for factors associated with breastmilk substitutes. Although the Code does not so state, these factors are not fully understood. The reasons for unsuccessful breast-feeding and early termination are important concerns. So far only vague and rudimentary answers have been identified, eg, "the milk dried up"49 or "lack of satisfaction."7 The decision-making process involved in early weaning has yet to be carefully analyzed. Certainly, biologic variables are involved, such as maternal nutritional status, maternal nutrient intake, and volume and quality of milk produced. These factors have not been well studied, and they are presumably influenced by psychological, social, cultural, and economic factors. Vahlquist,55 writing in the introduction to the WHO Collaborative Study on Breast-Feeding, noted, "Whereas, up to the 1960's it had been widely held that the decline in breast-feeding was a `fact of modern life,' this premise began to be increasingly questioned, and it was wondered whether the trend was really irreversible." The stakes in reversing the trend are great, as breast-feeding is the safest, most economical way to promote infant health and sound nutrition. Since then, the literature on the determinants of infant-feeding choice has grown rapidly.