This book brings together a total of 48 contributions (including 5 keynote papers) which were presented at the 2nd International Workshop on the Application of X-ray CT for Geomaterials (GeoX 2006) held in Aussois, France, on 4-7 October, 2006. The contributions cover a wide range of topics, from fundamental characterization of material behavior to applications in geotechnical and geoenvironmental engineering. Recent advances of X-ray technology, hardware and software are also discussed. As such, this will be valuable reading for anyone interested in the application of X-ray CT to geomaterials from both fundamental and applied perspectives.