Key principles underpinning feeding guidelines for preterm infants include support for developmental care, breastfeeding, milk expression, and creating feeding plans. Early trophic feeding with colostrum and transitional milk improves immune protection and promotes gut maturation. Studies of preterm infants demonstrate that feeding mother’s milk (MM) decreases the incidence of infection and necrotizing enterocolitis and improves neurodevelopmental outcome but may decrease ponderal and linear growth. Standard practice in neonatal units is to promote mother’s own milk as the feed of choice for all infants. However, it is not feasible or prudent to do so for all preterm infants. Mothers of preterm infants have lower rates of successful breastfeeding compared with those of term infants. MM can contain harmful bacterial or viral pathogens. Although preterm human milk (HM) contains higher concentrations of protein, sodium, zinc, and calcium than mature HM, it falls short of supplying adequate quantities of nutrients required by preterm infants. Therefore, HM supplemented with nutrients is recommended for all infants born before 32 weeks gestation and for certain infants born at 32-36 weeks of gestation. HM is the preferred feed, but preterm formula is an appropriate option when there is an inadequate supply of MM.