Congenital heart disease (CHD) and the need for life-saving heart surgery and intensive care during infancy may have effects on infant behavior and development. Children who require open heart surgery before their first birthday are vulnerable to developmental delays, especially related to motor skills (mobility) in the first year of life. Early delays in gross motor functioning (e.g., rolling, crawling, walking) have implications for learning and psychosocial development through adulthood. To date, no interventions to improve the gross motor functioning of children born with CHD have been developed. The purpose of this study is to learn more about developmental behaviors and to examine changes in developmental progress related to motor activities among a group of infants who received open heart surgery within the first three months of life. Activities will be tailored based on the individual infant's motor ability and medical status.