The correspondence in this collection concerns behavior genetics, evolution, heredity, etc. There is material relating to the congresses of the Permanent International Committee on Genetics, and the IXth (Bellagio, 1953), Xth (Montreal, 1958), and XIth (The Hague, 1963) International Congress of Genetics. There is also correspondence pertaining to the Cold Spring Harbor Symposium on Quantitative Biology (1955), the Mendel Semi-Centennial Symposium (1950), the Soviet geneticists' visit to the U.S. in 1967, and to Anton R. Zhebrak.