The Proceedings presented here contain the notes of lectures delivered during the Eleventh Winter School of Theoretical Physics, held at Karpacz, Poland, February 19 - March 4, 1974. The School was primarily devoted to new concepts in the theory of magnetism in metals, alloys, and metallic compounds, but, as can be seen from the table of contents of the book, other topics of the theory of magnetism were also discussed in the course of the lec­ tures. The organizers agreed to such a broadening of the scope in order to satisfy particular requests from the Polish participants for whose benefit the School was organized. These "local" interests are clearly reflected in the Proceedings and are responsible for a certain inhomogeneity of the topics selected for presentation. Nevertheless, we have a strong hope that these materials will be interesting to many physicists, not only in Poland, for the subjects discussed here are important not only on the local level, as the lectures contain quite fresh, unpublished results or excellent up­ to-date reviews. The first part of the volume contains lectures directly cor­ responding to the title of the School, i.e., selected topics of the theory of metallic magnetism, with slight bias toward rare earth and actinide metals and their compounds. In the second half we have collected the topics more loosely connected with the main­ stream, such as statistical and thermodynamic aspects of various models, spin-phonon interaction, and others.