Support is requested for organizing the fourth conference on Hemoglobin Switching. The conference is planned to take place in Airlie House, Virginia, September, 1984. It will represent a gathering of molecular biologists, cell biologists, developmental biologists and clinical investigators who are directly involved with studies on molecular biology of globin genes and hemopoietic cell differentiation. The duration of the conference will be three days. International participation is anticipated and support for travel and/or lodging expenses for 15 foreign and 40 USA participants is requested.