The primary objective of this twelfth edition of the Santé publique France Barometer was to produce regional estimates on topics that have historically been tracked in the Barometer (substance use, vaccination, nutrition). The large sample size planned for this purpose was also intended to enable the production of estimates and interpretive insights on localized issues (such as pesticides, for example), rare events (such as suicidal behavior or musculoskeletal disorders), or specific populations (such as pregnant women or parents). The investigation into perceptions of environmental health risks and the level of information among the French public regarding these risks, which began in 2019, was also set to continue. However, the implementation of the first lockdown measures aimed at curbing the COVID-19 epidemic severely disrupted fieldwork, which had to be suspended before the desired sample size could be reached. Since the sample size achieved was sufficient to conduct analyses at the national level, it was decided to halt the survey. Instead of resuming the survey after the lockdown, a new survey was launched with a smaller sample and a streamlined questionnaire that included topics related to the pandemic. This approach allowed for a responsive survey of the population in this exceptional health context. The methodology used for the 2020 edition is identical to that of 2019, which is available online. The survey scope, expanded to include 18- to 85-year-olds in 2019, was maintained in 2020. This document specifies the survey scope, its fieldwork dates, the target population and its age range, the main themes (environmental health, addictions, vaccination, nutrition, health of the elderly, mental health, accidents), the sampling plan and bases, the data collection method, the sample size (9,178 before lockdown, 5,695 after), the overall response rate, the calculation of the response rate, and the weighting of survey interviews.