Discs occurring in a wide diversity of astronomical objects prompt similar questions about their dynamical behaviour. Astrophysicists working on problems related to just one type of disc may find that a similar problem has already been addressed in a different context. This is especially true of the dynamical behaviour: the dispersion relation for spiral density waves was originally derived for galaxies but has been applied, with more success even, to Saturn's rings, the formalism of a global mode treatment for gaseous accretions discs has some similarity to that for the collisionless stellar discs of galaxies, aspects of the dynamics of planet formation around a young stellar object are reflected in the response of a galaxy disc to a co-orbiting giant molecular cloud complex, etc.

In order to encourage thinking along these lines, the Department of Astronomy in the University of Manchester organised a four day conference in December 1988 to bring together experts on discs in a number of contexts. In rough order of increasing physical size, these are: planetary ring systems, accretion discs in cataclysmic binary stars and active galactic nuclei, protoplanetary and protostellar discs and disc galaxies.

The aim of the conference, and of these proceedings, was to present those aspects of the behaviour of each type of disc that could be of relevance to other types. To emphasise this theme, the sequence of talks was deliberately arranged so as ensure that many different disc types were discussed on any one day.