Breastfeeding continues to steadily increase in the US, with 83.2% of infants in 2019 breastfed for some duration. Strong evidence supports health benefits of breastfeeding for both mother and infants. Indeed, human milk is considered the ideal source of nutrition for infants worldwide. Despite this, there are significant knowledge gaps in our understanding of the nutritional composition of human milk. Without better knowledge of this infant food that for many represents the only food or fluid for the first six months of life, community, clinical and research RDNs remain challenged in defining and implementing best practices for infant nutrition. In fact, this knowledge gap impairs infant nutrition for both breastfed infants and even infants who receive nutrition through breastmilk substitutes modeled on our understanding of human milk. This session, guided by human milk experts, will discuss current limitations of our human milk composition understanding; summarize the best available evidence regarding human milk macronutrient, micronutrients, and bioactive factors; identify important directions of future research, including areas where RDNs have unique contributions; and translate the implications of this information for RDNs whose practice includes lactating women and any infant, breastfed or otherwise.