 Thalassemia is an inherited blood disorder in which the body makes an abnormal form of hemoglobinthe protein in red blood cells that carries oxygen. People with thalassemia often experience fatigue, shortness of breath, and pain. There have been no previous research studies that have fully examined pain levels in people with thalassemia, and as a result, the sources of pain remain unknown. This study is a substudy of the Assessment of Pain study, which is a Thalassemia Clinical Research Network TCRN study that is examining the prevalence and severity of pain in people with transfusion-dependent thalassemia and non-transfusion-dependant thalassemia. This study will enroll a subset of participants from the Assessment of Pain study who have transfusion-dependant thalassemia. The purpose of this study is to examine whether pain varies during the blood transfusion cycle and whether the length of the transfusion cycle affects pain levels in people with transfusion-dependent thalassemia. 