The purpose of this report is to summarize the literature concerning the relationship of breastfeeding and various infant and maternal health outcomes. Two key questions are addressed: 1. What are the benefits and harms for infants and children in terms of short-term outcomes, such as infectious diseases (including otitis media, diarrhea, and lower respiratory tract infections), sudden infant death syndrome (SIDS) and infant mortality, and longer term outcomes such as cognitive development, childhood cancer (including leukemia), type I and II diabetes, asthma, atopic dermatitis, cardiovascular disease (including hypertension), hyperlipidemia, and obesity, compared among those who mostly breastfeed, mostly formula feed, and mixed feed; and how are these outcomes associated with duration of the type of feeding? Do the harms and benefits differ for any specific subpopulations based on socio-demographic factors? 2. What are the benefits and harms on maternal health short-term outcomes, such as postpartum depression and return to pre-pregnancy weight, and long-term outcomes, such as breast cancer, ovarian cancer, diabetes and osteoporosis, compared among breastfeeding, formula feeding, and mixed feeding, and how are these associated with duration of the type of feeding? Do the harms and benefits differ for any specific subpopulations based on socio-demographic factors?