There has been much controversy about the impact of the health sector and the infant food industry on breast-feeding behavior. This study links causal factors to breast-feeding decisions, using a longitudinal survey of more than 3,000 Filipino mother-infant pairs. Most factors decreasing the likelihood that mothers will breast-feed seem to be related to family economics. Delivery in a private hospital, urban residence, high income, absence of spouse, and having worked for wages affect adversely the initiation of breast-feeding. Formula advertising and distribution of samples appear to have relatively little impact on feeding decisions.