This thesis seeks to demonstrate that the new facilities of Web of Science (WoS) online can be used in new ways to enhance understanding of scholarly communication. It investigates four aspects of scholarly communication: characteristics of highly cited articles, citation levels of collaborative articles, citation levels of multi-disciplinary articles, and patterns of annual citation of highly cited articles. For the first two topics it investigates the WoS category of ‘Information Science & Library Science’ (IS&LS), whereas for the other topics it compares diverse WoS categories in science and social science. Although its main data source is WoS, its investigation of disciplinarity also uses Scopus. The thesis finds: (a) Highly cited IS&LS articles tend to be multidisciplinary and cited late, but are not necessarily first-authored by influential IS&LS researchers, (b) Amongst un-cite IS&LS articles the proportion of collaborative articles has remained almost constant over the past three decades whereas for higher cited articles it has grown steadily with time, (C) In social science subjects the level of citation of multi-disciplinary research are generally similar to that of mono-disciplinary research, whereas in science the citations levels for multi-disciplinary research are substantially lower than that of mono-disciplinary research, and (d) In both science and social science many very highly cited articles continue to be heavily cited more than twenty years after publication. This thesis also introduces and uses an indicator for measuring the extent of collaboration called ‘average partner scores’ and indicates a way in which the subject categories of WoS can be investigated without requiring a licence for the WoS database. Finally, it identifies and addresses some of the technical problems of using WoS online to investigate scholarly communication.