The MILQ Study is a large multicenter research effort conducted across Bangladesh, Brazil, Denmark, and The Gambia that systematically measured human milk nutrient concentrations and milk volume throughout the first 8.5 months of lactation in 1,242 healthy, wellnourished mother–infant dyads. By combining validated analytical methods for quantifying macro and micronutrient concentrations in milk with precise measures of milk volume transferred to infants, the study generated comprehensive reference values and percentile curves for milk nutrient composition and infant nutrient intake from milk over time. These data address longstanding gaps in reliable human milk composition information and values against which to evaluate need for and impact of maternal supplementation programs, provide a robust foundation for updating nutrient intake recommendations for infants and lactating women, and serve as a valuable resource for improving maternal and infant nutrition strategies worldwide.