The Advanced Study Institute on "Theoretical Aspects and New Developments in Magneto-Optics" was held at the University of Antwerpen (R.U.C.A.), from July 16 to July 28, 1979. The Institute was sponsored by NATO. Co-sponsors were: Agfa-Gevaert (Belgium), A.S.L.K. (Belgium), Bell Telephone Mfg. CO. (Belgium), Esso Belgium, Generale Bankmaatschappij (Belgium), General Motors (Belgium), I.B.M. (Belgium), Kredietbank (Belgium), Metallurgie Hoboken-Over pelt (Belgium), National Science Foundation (U.S.A). A total of 60 lecturers and participants attended the Institute. Scope of the Institute The magneto-optic phenomena are due to the change of the polarizability of a substance as a result of the splitting of the quantized energy bands. Most of these phenomena were discovered during the second half of this century. The understanding of the magneto-optical effects of all kinds, however, was brought by the advent of quantum mechanics, and since then important progress has been made in many fields of experimental methods and techniques.