MAJOR ADVANCES IN MEDICAL TECHNOLOGY, SUCH as chemotherapy, bone marrow transplantation, and immunotherapy, have increased survival rates and changed the lives of ill children and their families. One consequence of these advances in medical care has been that many children have experienced multiple, intensive, long-term hospitalizations. Despite pressures from insurers to shorten lengths of stay, children with serious chronic conditions can spend much of their childhood in a hospital. In 2000, approximately 2 million children and adolescents were hospitalized for pediatric illness. It also has been estimated that “childhood disability” accounts for 5 million hospital days each year. These illnesses can range from relatively common pediatric diagnoses such as sickle cell disease, severe asthma, and cystic fibrosis, to rare conditions such as immunodeficiencies, cancer, and unusual genetic syndromes. Prolonged hospitalizations, though necessary for adequate medical care, change the physical and emotional environment, disciplinary context, schooling, family life, and neurobiology of the chronically ill child. Thoughtful and integrated multidisciplinary care is more important today than ever before. Physicians and hospital staff should realize that many children with chronic conditions are growing up in the hospital and that these hospital experiences can profoundly affect their cognitive, emotional, social, and sexual developmental trajectories. With this understanding, the hospital environment and clinical approach must be modified to optimize development. An important goal for these children and adolescents is to normalize hospital life as much as possible. Parents rooming in with infants and children, the creation of Child Life programs in hospitals, and universal pain assessment are examples of changes in the hospital environment that take into account developmental considerations. Parents, initially focused on life-threatening physical concerns, often later express deep gratitude for these interventions and are eager for additional support of their child’s psychosocial development. Although such initiatives have been valuable contributions to the environment of care, additional practices should be adopted to help these children. The focus of this Commentary is limited to the impact of frequent or prolonged hospitalization on medically ill children since so little is known about children’s experiences during transitions between inpatient and outpatient settings.