Adriaan Blaauw; Emeritus Professor of Astronomy at the Universities of Groningen and Leiden, former Directo.r of the Kapteyn Laboratory and of the European Southern Observatory, celebrated his 70th anniversary on 12 April 1984. To mark this event, an international Symposium was con- vened on the subject "Birth and Evolution of Massive Stars and Stellar Groups", a subject which has played the leading role in Blaauw's scien- tific research. The present volume contains the Scientific Proceedings of that Symposium. The meeting was organized by a Committee consisting of: W.H.W.M. Boland...