The 39th Annual Denver X-Ray Conference on Applications of X-Ray Analysis was held July 30 -August 3, 1990, at the Sheraton Steamboat Resort and Conference Center, Steamboat Springs, Colorado. The "Denver Conference" is recognized to be a major event in the x-ray analysis field, bringing together scientists and engineers from around the world to discuss the state of the art in x-ray applications as well as indications for future developments. In recent years there has been a steady expansion of applications of x-ray analysis to characterize surfaces and thin films. To introduce the audience to one of the exciting and important new developments in x-ray fluorescence, the topic for the Plenary Session of the 1990 Conference was: "Surface and Near-Surface X-Ray Spectroscopy. " The Conference had the privilege of inviting five leading world experts in the field of x-ray spectroscopy to deliver lectures at the Plenary Session. The first two lectures were on total-reflection x-ray fluorescence spectrometry. Professor P. Wobrauschek of Austria reviewed "Recent Developments and Results in Total-Reflection X-Ray Fluorescence. " Trends and applications of the technique were also discussed. Dr. T. Arai of Japan reported on "Surface and Near-Surface Analysis of Silicon Wafers by Total Reflection X-Ray Fluorescence. " He emphasized the importance of using proper x-ray optics to achieve high signal-to-noise ratios. A mathematical model relating the x-ray intensity to the depth of x-ray penetration was also described.