Papers document Aage Bohr's personal research as well as the development of the Niels Bohr Institute, a world center for nuclear physics, as well as other areas of theoretical physics. The correspondence, which comprises the bulk of the papers, covers the period 1950-1980, and includes in-coming as well as out-going letters. There are about 3100 correspondents, of which about 600 are considered to be of special importance. It includes material on the Institute's connections with Eastern, particularly Soviet and Chinese, physics and physicists at a time when East-West relations were practically blocked. Addition of 19 boxes contains scientific and administrative correspondence from 1981-1993 (8 boxes), and materials regarding funding and international cooperation, particularly with Eastern Bloc countries from 1965-1980 (11 boxes).