The purpose of this study is to see how full-term and pre-term infants' brains relate to their movement and development throughout the first two years of life. All infants who participate in this study will have a magnetic resonance image (MRI) of the brain prior to discharge from the hospital. Infants will then have follow-up appointments every 3-6 months at home or at the Infant Motor Behavior Laboratory at the University of Delaware. The follow-up sessions will test how infants change their movements to respond to interesting objects or sounds in their environment. It is hoped that the results of this study will assist clinicians in developing better testing and treatment methods for those infants at risk for developmental problems.