The collection is comprised of Rossi's work in radiation measurement, particularly his work with the International Commission on Radiation Units and Measurements (ICRU) and the National Council on Radiation Protection and Measurements (NCRP). Materials date from 1948 to 1986. Also included are research materials, including laboratory notebooks and charts. Some copies of Rossi's published papers, along with earlier drafts and lecture notes are present as well. Rossi's work with various committees, such as the National Research Council Committee on the Biological Effects of Ionizing Radiation (BEIR), the Radiation Research Society, and the Tactical Advisory Committee on Radiation to the Commissioner of Health in New York City, as well as others, are included in series 5. Most of the correspondence is sorted by date, but a small amount of it is by recipient. There is a small amount of student files.