Human immunodeficiency virus (HIV) transmission through breast milk potentially begins with the first exposure to breast milk. Policies on HIV and infant feeding have been based on the child survival benefits of breastfeeding, which have been well documented and appreciated. During lactogenesis I, mammary alveolar epithelial cells differentiate into secretory cells, fat droplets accumulate, and the concentration of lactose and lactalbumin increases in alveolar cells. Immune therapy and vaccination are current innovations being investigated to reduce postnatal transmission from mother to child though breastfeeding. The field of infant feeding and HIV has changed considerably since the 1990s, with the pendulum now swinging in favor of breastfeeding with antiretroviral therapy for HIV-infected mothers, as breastfeeding is a critical child survival strategy. Infant feeding and HIV must be viewed within the broader context of child survival and not just in terms of the prevention or elimination of vertical HIV transmission.