The idea of organizing a joint discussion on the impact of ultraviolet observations on spectral classification arose during the IAU symposium n»72 held at Lausanne, in the honour of W.W. Morgan. It became evident at that time that the wealth of spectroscopic and spectrometric data already obtained from various orbiting telescopes should shed some new light on the problem of spectral classification. I whish to thank here the members of the Organizing Committee who planned this Joint Discussion: W.P. Bidelman, A.D. Code, C. Jaschek, and K. Nandy. I also thank the authors of invited reports and contributed papers, as well as those who participated in the discussions.