The theme of the conference held at the Institute of Astronomy in the summer of 1981 was 'Supernovae'. The topic was interpreted very broadly: observations in all wavebands were discussed, along with theories for the explosion mechanism and the light curves; there were papers on supernova remnants and pulsar statistics; other sessions dealt with the use of new techniques for improving supernova searches, and with the importance of supernovae for cosmogonic and cosmological studies. This book contains texts based on all the main review lectures, together with a number of shorter papers which describe new results presented at the conference. The Scientific Organising Committee, responsible for arranging the programme, consisted of J. Audouze, G. B. Brown, J. Danziger, F. Pacini, M. J. Rees (Chairman) and J. W. Truran. The conference was well attended, with over 100 visitors to Cambridge as well as many local participants. We are grateful to all those who helped with the practical organisation of the meeting, especially Dr Michael Ingham (Secretary of the Institute of Astronomy) and Mrs Norah Tate. We thank all the authors of the papers in this volume for the trouble they took in preparing written versions of their excellent lectures, and for the efforts they made to meet our ' final' deadl ine: we wish especially to thank Drs W. O. Arnett and J. M. Lattimer for help with the edi torial work.