During the week of June 6-9, 1978, a group of 36 physicists from 15 countries met in Erice, Sicily, for the first specialized seminar on "Interacting Bosons in Nuclear Physics". The countries represented were Argentina, Belgium, Denmark, Finland, France, the Federal Republic of Germany, Israel, Italy, Japan, the Netherlands, Poland, Sweden, the United Kingdom, the United States of America and Yugoslavia. The Seminar was sponsored by the Italian Ministry of Public Education (MPI), the Italian Ministry of Scientific and Technological Research (MRST), the North Atlantic Treaty Organiza­ tion (NATO) and the Regional Sicilian Government (ERS). The purpose of the Seminar was to discuss the present status of the Interacting Boson Model both from the theoretical and experi­ mental point of view. Some of the lectures presented in this book summarize particular aspects of the model and are based on previously published work (F. Iachello, R. F. Casten, Z. Sujkowski, L. Hassel­ gren, H. Emling, I. Talmi, T. Otsuka, J. McGrory, A.E.L. Dieperink and A. Arima). Others are entirely new. In particular, the lec­ tures of O. Scholten and A. Gelberg and V. Kaup present the first extensive set of calculations based on the proton-neutron boson model, while the lecture of J.N.Ginocchio describes a fermion model with properties identical to those of the interacting boson model. Also new are the le~tures of D. R. Bes, R. A. Broglia and P. F.