The purpose of this study is to evaluate the FIM™ as a measure of daily function in children with sickle cell disease hospitalized with vasoocclusive pain. Currently, the standard for pain assessment is a rating of pain intensity, as determined by observation (for younger children) or self-report (for older children and adolescents). However, these measures of pain intensity are not effective in recurrent or chronic pain states, and in sickle cell disease in particular. Pediatric patients who are hospitalized with vasoocclusive pain often do not report a decrease in pain intensity; however, other indications of clinical status, such as ambulation, less use of opiates from the patient-controlled analgesia (PCA) pump, increased food intake, and transition to oral pain medication, signify that the patient may be improving. As a result of our inability to get an accurate picture of the patients' condition, we would like to have a summary of improvement that would reflect these changes in clinical status and reflect the reduced impact of sickle cell pain on the patient's life. In this study, we plan to evaluate a standardized functional assessment measure in pediatric patients with sickle cell disease. It is hypothesized that FIM™ scores will correlate with other indicators of clinical status, such as movement, quality of sleep, use of IV opiates from the patient-controlled analgesia (PCA) pump, and use of intravenous vs. oral pain medications. It is also hypothesized that the FIM™ will demonstrate adequate responsiveness to change in functional status within a 3-7 day hospitalization by a progressive increase in scores and associations with other indicators of clinical improvement.