There is strong evidence that maternal breast milk feedings in infancy confer multiple health benefits in the extremely preterm population (extremely low birth weight, ELBW, <1000 g). Studies suggest an IQ advantage of up to 8 points conferred by maternal milk feeding in this population. Rates of sepsis and necrotizing enterocolitis are also lower in human milk fed ELBW infants, and they experience shorter hospital stays and fewer re-hospitalizations in the first year of life. When mothers choose not to or are unable to provide milk, preterm formula is usually used. Recently, pasteurized donor human milk is available in some NICUs in the US as an alternative to preterm formula. Donor milk has not been well studied with regard to its safety and efficacy. It is unknown if donor human milk confers the same benefits as maternal milk with regard to neurodevelopmental and health outcomes. The proposed study will be the first US multicenter randomized trial of the health and developmental effects of donor milk as compared to preterm formula in ELBW infants receiving little or no maternal milk. Our long-term goal is to optimize neurodevelopmental and health outcomes for ELBW infants, maximizing their quality of life and societal functionality throughout their lives. If donor human milk has similar effects to maternal milk, the public health benefit of donor milk feedings in ELBW infants unable to receive maternal milk would be considerable.