Vaccination coverage among adolescents in France is insufficient, whether it concerns catch-up vaccinations for childhood vaccines or vaccinations recommended for this age group. A qualitative study, based on semi-structured individual interviews, was conducted with a sample of 30 general practitioners in France who treat adolescents, to understand the barriers to vaccination recommendations in this age group and to identify areas for improvement. The results suggest that insufficient vaccination coverage among adolescents is rarely due to a lack of support for vaccination in this age group on the part of physicians. Rather, it appears to reflect contextual barriers such as the difficulty of incorporating this topic into the infrequent consultations with adolescents—which are most often prompted by other reasons—time constraints during these consultations, some vaccine hesitancy among parents, and the perception among many doctors that these vaccines are non-urgent. This latter perception is reinforced by the broad age ranges covered by vaccination recommendations for adolescents. Finally, the changing nature of the vaccination schedule sometimes appears to be a barrier, particularly regarding the adoption of new vaccinations. In this regard, the development of materials better suited to the constraints of general practice would make it easier to address this topic during consultations. A discussion on shifting from an age-range approach to one of fixed ages for vaccination recommendations could be initiated. Finally, promoting regular medical check-ups for adolescents would provide a suitable opportunity for general practitioners to propose vaccinations.