Among the ten steps to successful breastfeeding advocated by the WHO and UNICEF, steps six and nine clearly state that formula supplementation and pacifier use, except when medically necessary, should be avoided. Early formula supplementation may not only interfere with the mother's lactation but also result in nipple confusion on the part of the baby. To avoid nipple confusion, the encouragement of cup feeding and the non-provision of pacifiers or bottles are required nursing practice in baby-friendly hospitals. However, the relationship between nipple confusion and the duration of breastfeeding has not been well examined. The purpose of this paper is to explore the relationships between three methods of feeding (i.e. pacifier, bottle feeding, and cup feeding), nipple confusion, and duration of breastfeeding. A hypothetical framework is proposed to explain these relationships on the basis of a review of the literature.