IAU Symposium 103 was held at University College London, August 9-13 1982. This volume contains the proceedings of the meetin- invited papers, abstracts of contributed papers, and discussion. As is nON custanary with the proceedings of IAU Symposia, the manuscript was canpiled fran camera-ready copy. The Editor was responsible for the preparation of the abstracts of the contributed papers and the discussion, the authors of the invited papers for the preparation of their 0Nn reviews. The discussion at the meeting was lively and infonnative, and the Editor hopes that a reasonably faithful and readable record of the discussion is to be found in these proceedings. In accordance with the wish of the Scientific Organising Committee, an object index has been canpiled and appended. It is to be hoped that the index will augment the usefulness of the volune. The Editor is greatly indebted to M. J. Barlow for his help in preparing the index. Financial assistance for the meeting was provided by the IAU and University College London. The hospitality received during the excursion to the Old Royal Observatory and National Maritime MUseum, Greenwich, is gratefully acknowledged. The task of editing these proceedings has been greatly facilitated by the excellent secretarial assistance of V. A. Kerr. David Flower Durham, October 1982 xiii D. R. Flower (ed.), Planetary Nebulae, xiii.