The proceedings of the 14th International Workshop on Condensed Matter Theories, held June 1990, on the Island of Elba, Italy, which brought together scientists from different areas of condensed matter, such as quantum fluids, atoms and molecules, high-Tc superconductivity, and nuclear physics. The papers are grouped under the topics of formal methods, quantum fluids, electronic systems, atoms and molecules, high-Tc superconductivity, lattice theories, and nuclear physics. Annotation copyright Book News, Inc. Portland, Or.