This manual provides a harmonized approach to quality assurance (QA) in the emerging area of digital mammography. It outlines the principles of, and specific instructions that can be used for, a QA programme for the optimal detection of early stage breast cancer within a digital environment. Intended for use by Member States that are now using digital mammography or that are assessing the implications of using digital mammography, it addresses major areas such as considerations concerning the transition from screen film to digital mammography, basic principles of QA, clinical image quality, quality control tests for radiographers, and quality control tests for medical physicists, including dosimetry assessment. Instructional materials to supplement the knowledge of professionals already working in the field of diagnostic radiology, as well as quality control worksheets, are also provided.