The Sixth International Symposium on Gas Flow and Chemical Lasers (GCL) was held in Jerusalem, Israel, on September 8-12, 1986. The charm and beauty of Jerusalem and the unique blending of ancient and modern made this Symposium an enjoyable experience for the 165 participants and the accompanying persons. Yet, it seems that the invited and contributed papers presented at the Symposium were equally attractive so that most of the participants attended most sessions, resisting the temptations outside the session hall. Indeed, many speakers presented up-to-date results that were obtained, or cleared, just a few days before the Symposium. This volume is a compi­ lation of 19 invited and 61 contributed papers and of a panel discussion on the prospects for short wavelength chemical lasers held at the closing session of the Symposium. This discussion is presented as recorded in order to re­ tain the flavour of spontaneous presentation at the risk - or advantage - of presenting some venturous ideas, and the danger of misquoting. In editing the book, a deductive approach has been attempted. The book starts with some fundamental issues, namely fluid dynamics and optics, and then deals with the design, diagnostics, propagation and applications of various gas laser systems, covering the wavelength spectrum from XUV to infrared. Then follow recent developments of general interest to the laser community and the book concludes with an eye to the future, i.e., with a section on short wavelength chemical lasers.