This methodological guide for evaluating the national organized breast cancer screening program is intended for departmental screening management organizations. These organizations implement the program at the local level and collect data on the participation and follow-up of screened women. The objective of this guide is to ensure the quality of the evaluation and, more specifically, the consistency of data across departments. It is these data—transmitted from the 100 departments to the French Institute for Public Health Surveillance, which validates and aggregates them into an annual national database—that enable the calculation of the program’s evaluation indicators. (R.A.)