This book constitutes the refereed proceedings of the 9th International Workshop on Digital Mammography, IWDM 2008, held in Tucson, AZ, USA, in July 2008. The 70 revised full papers and 34 revised poster papers presented were carefully reviewed and selected from numerous submissions for inclusion in the book. The papers are organized in topical sections on breast density, texture and risk, clinical experiences chair, breast imaging physics, image analysis and CAD, modeling and simulation, digital breast tomosynthesis, as well as physics, image quality and quality assurance.