Children who receive hematopoietic cell transplants (HCT) are at high nutritional risk due to comorbidities and complications that are likely to develop before, during and after transplant. Prior to transplant, many children undergo multiple rounds of chemotherapy which affect appetite and cause gastrointestinal toxicities that limit food intake. During transplant, painful mucositis makes it difficult to consume adequate nutrients and often children will require nutrition support such as parenteral or enteral nutrition. Energy imbalance and physical deconditioning following transplant can result in loss of lean body mass and functional impairment; these nutritional side effects are exacerbated if the child develops graft-versus-host disease. After transplant, a substantial number of childhood cancer survivors become overweight and develop metabolic syndrome. However, little is known about the prevalence and distribution of pediatric malnutrition (under-nutrition as well as obesity), the psychosocial factors that affect dietary intake and how the quality of the child's food intake and physical activity level throughout the transplant process might affect body composition and clinical outcomes. In this exploratory study, we will monitor nutritional status in pediatric patients undergoing HCT. This study will test the feasibility of collecting patient-reported dietary intake data along with anthropometric, body composition, functional status and psychosocial measurements that may influence dietary intake in pediatric patients undergoing HCT. The data collected in this preliminary analysis will inform future interventional studies.