This volume contains the lectures of "Earlier and Recent Aspects of Super­ conductivity", the 18th course of the International School of Materials Science and Technology, which was held at the Ettore Majorana Centre for Scientific Culture in Erice (Sicily), Italy, July 4-16, 1989. In the wake of the discovery of high-Tc oxides many international confer­ ences have been held on the subject, mainly intended for those already working in high-Tc research. Hence, the idea evolved of organizing a school dedicated to students and young scientists entering the field of superconductivity. The intention was to give a broad perspective of the field with its eight decades of research history and thus to link existing fields of knowledge and gain con­ tinuity. The new high-Tc cuprates were integrated, both historically and by subject, into the field of classical superconductivity, as well as into its newer branches of heavy-fermion, organic and chalcogenide superconductors. Even the organizers and the lecturers were surprised how many cross-links became apparent between the different branches of superconductivity. The lectures have been grouped into four parts, namely: - Fundamental properties of superconductors - Coherence-length-related properties - Electronic and magnetic properties - Theoretical models The number of applications from potential participants greatly exceeded the capacity of the facilities available. Ultimately, 100 students from 25 countries were selected to attend the course. The remarkable surroundings of the medieval town of Erice promoted a most stimulating but nevertheless relaxed atmosphere.