The Fourth International Conference on Plasma Physics and Controlled Nuclear Fusion Research, organized by the International Atomic Energy Agency, was held during the summer of this year in the United States of America - in the small university town of Madison, in the state of Wisconsin. Some 500 scientists from about 30 countries took part in the Conference and approximately 140 papers were discussed, considerable use having been made of the rapporteur system. As at the earlier conferences in this series, most of the papers described experimental work.