1) ESAs administered to preterm infants during the neonatal period improve long-term neurodevelopmental outcome, 2) ESAs affect regional brain structure, neurochemistry and neurologic organization as reflected in magnetic resonance (MR) imaging, and 3) the blood level of ESA correlates with MR imaging and neurodevelopmental outcome. To test these hypotheses, neurodevelopmental outcome will be assessed through a comprehensive neurodevelopmental assessment at two time points: 42-48 months, and 66-72 months (WPSSI III, Early Child Assessment, Executive Categorization Battery). Brain imaging will be performed concurrent with developmental assessments and includes measures of volume (high resolution volumetric analysis), neurochemistry (magnetic resonance spectroscopy) and regional cerebral blood flow (arterial spin labeling). This study is highly clinically relevant due to the long-term developmental and imaging follow up studies that are part of the design, significantly increasing our ability to determine if developmental, functional and anatomical differences exist in infants randomized to ESAs, a relatively new interventional strategy used in preterm infants. This proposal addresses our long-term goal of developing effective treatment strategies for disorders associated with prematurity through an improved understanding of brain-behavioral relationships.