This collection consisting of correspondence, unpublished papers, research notebooks, and reprints is divided into two parts: Part I includes correspondence which is broken down into two chronological divisions; the first, spanning 1928-1937, includes copies of letters from P. Blackett, F. Bloch (1932), Niels Bohr (1934-1936); H. Casimir (1929); Paul Dirac (1928-1936); Paul Ehrenfest (1926-1932); T. Ehrenfest (daughter of P. Ehrenfest, 1928-1937); W. Elsasser (1928-); W. Heitler (1929, 1932); P. Jordan (1931); F. Klein (1929); J. Cockroft (1931-1932); Alfred Land ̌(1934); N. Mott (1931, 1935), Ch. Moller, H. A. Lorentz (1927), R. Peierls (1932); A. Sommerfeld (1937). Russian physicists represented include: L. I. Mandel'stamm (1928-1943); V. A. Fock (1929-1955); D. V. Skobel'tzyn (1938), and N. N. Andreyev. Also Tamm's letters of 1928 and 1931 to his wife during visits to Germany and England. Part 2 includes: Correspondence, 1955-1971. Correspondents are: Hans Bethe, O. Chamberlain, F. Dyson, Drell, W. Heisenberg, L. Infeld, Flowers, C. Moller, J. Robert Oppenheimer, A. Pais, I. Prigogine, M. Gell-mann, R. Marshak, A. Salam, E. Segr,̈ S. Sakata, Hideki Yukawa, Victor Weisskopf, and Leo Szilard. Russian physicists represented include S. A. Altschuller, V. L. Ginzburg, E. L. Feinberg, and Da. A. Krizhnitx. Also includes letters from Russian biologists: Lederberg, A. A. Liybischev, V. N. Sukashev, V. A. Engelgardt; chemist, A. N. Frumkin; and letters from the Solvay and Nobel committees. The unpublished papers on physics span several years; those on biological matters date from the 1950s and 1960s. The research notebooks are from 1925-1927, 1931-1935, 1938-1940, and 1953. The reprints are of papers by Tamm and other physicists.Bibliography: "Igor Evegenevich Tamm," Moscow: Nauka publ., 1974.