The past forty years have been a time of spectacular development in the study of general relativity and cosmology. A special role in this has been played by the influential research groups led by Dennis Sciama in Cambridge, Oxford, and Trieste. In April 1992 many of his ex-students and collaborators came to Trieste (where he is currently Professor) for a review meeting to celebrate his 65th birthday. This book consists of written versions of the talks presented which, taken together, comprise an authoritative overview of developments which have taken place during his career to date. The topics covered include fundamental questions in general relativity and cosmology, black holes, active galactic nuclei, galactic structure, dark matter, and large scale structure.