Early in 1988, an agreement was reached by the European Community, Japan, the United States of America and the Soviet Union to jointly conduct conceptual design activities for the International Thermonuclear Experimental Reactor (ITER) until the end of 1990, under the auspices of the International Atomic Energy Agency. Since May 1988, participants from the four Parties meet regularly in Garching, Federal Republic of Germany, to carry out the design work. On the basis of the investigation results obtained so far, a concept for ITER has been defined which incorporates the maximum possible flexibility of the device and allows a variety of plasma configurations and operating scenarios to be adopted. For the technology experiments, with a full breeding blanket, the device can be operated typically with a plasma carrying a current of 18 MA at a major radius of 5.5 m. For the plasma physics experiments, the device can be configured with a thinner shield, if required, and it can produce a plasma of 22 MA with fully inductive operation and higher currents under limited technical conditions. A list of important specific physics and technology research and development tasks for ITER has been prepared and these tasks are being