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 coun­ tries were selected to attend the course. The remarkable surroundings of the medieval town of Erice promoted a most stimulating but nevertheless relaxed atmosphere.