This review presents the effects of delayed umbilical cord clamping on neonatal transitional physiology. The effects of delayed cord clamping on short- and long-term neonatal outcomes are then discussed. There is ample evidence over the last 50 years that delayed cord clamping in preterm infants is beneficial for both short-term and long-term outcomes. Providing ventilation in the initial steps of neonatal resuscitation prior to clamping of the umbilical cord has a physiologic basis and results in better outcomes for newborns. The challenge now is to design equipment and strategies that can allow initial resuscitation very close to the mother while the umbilical cord is still attached to the placenta.