Introduction: Routine data on vaccination coverage (VC) among adolescents are scarce at the subnational level in France. However, it is important for regional health agencies to have accurate indicators at the level of their health regions in order to implement policies promoting vaccination and launch targeted catch-up campaigns. The objectives of this study were to document the VC of adolescents in the departments of Calvados and Orne (Normandy), as well as their knowledge and perceptions regarding vaccination and vaccine-preventable diseases. Methods: A descriptive cross-sectional study measuring the VC of adolescents summoned to several “Citizen Defense Days,” who were asked to bring their health records. In addition, data on their knowledge, attitudes, and perceptions regarding vaccination were collected via a self-administered questionnaire. Results: Vaccination coverage was similar in both departments: two-thirds of adolescents had received two pertussis booster doses; MMR (measles, mumps, rubella) vaccination coverage with two doses was over 90%; less than a quarter had received the catch-up dose against meningococcal C; one-third had received three doses of hepatitis B vaccine, and a quarter of adolescent girls had received two doses of HPV vaccine. A large majority of adolescents in both departments considered vaccination "useful" or "very useful." Conclusion: The vaccination coverage rates measured among adolescents in Calvados and Orne are insufficient for certain vaccines, requiring the implementation of targeted catch-up campaigns. Adolescents view vaccination fairly positively but lack awareness of the diseases against which they are or could be vaccinated.