At the Denver X-Ray Conference, the topic for the plenary lectures alternates annually between x-ray diffraction and x-ray fluorescence. This year is a "diffraction" year, and the theme is accuracy in powder diffraction. Instead of comprehensive cover age, such as was attempted at the Accuracy in Powder Diffraction Meeting held at the National Bureau of Standards in 1978, this meeting focuses on recent developments in measurement accuracy of two-theta and intensity. The focus on accuracy, from the practical point of view, is important in a wide range of x-ray diffraction measurements. Accu rate data improve our ability to identify phases in a mixture using the Powder Diffraction File. Improved accuracy is essential for better characterization of the lattice, crystallite size, strain and structure. Finally, the accuracy of quantitative analysis is of great concern in many laboratories. The five invited papers of the plenary session give a broad perspective of recent activity throughout the world on uses of more accurate data, on methods to achieve greater accuracy, and on fundamental factors affecting the accuracy. The scope of the conference, however, is much broader than that of the plenary session. The workshops lead off with many practical aspects of x-ray analysis. Many of the contributed papers expand on the theme of accuracy in x-ray powder diffraction. In particular, the s.ession on XRD quantitative phase analysis provides an exception al coverage of the limitations in quantitative analysis and of the techniques being employed to improve the results."