Teachers' beliefs about their ability to support pupils' career development skills (Teacher Career-Related Support Self-Efficacy) are a key element of vocational guidance practices in school (Joho et al., 2024). Yet, this construct remains underexplored in the French-speaking context, due to a lack of validated French psychometric tools. The purpose of this study is to adapt and validate the French version of an Italian questionnaire (Parola et al., 2023), in order to assess a professional development program that trains teachers in career guidance and accompanies pupils in developing career-related skills. Following established guidelines for scale adaptation and validation (Boateng et al., 2018), the instrument underwent translation and independent back-translation, peer review by experts in vocational guidance and educational sciences, and iterative adaptation to the French-speaking Belgian cultural context. The main challenges for this questionnaire's adaptation involved balancing translation fidelity with functional needs, context and cultural adaptations. The study sample consists of approximately 50 secondary-school teachers from 10 schools in French-speaking Belgium. Internal consistency, reliability, and construct validity will be examined using standard psychometric procedures. The questionnaire will be administered twice (October 2025, pre-training and April 2026, post-training). The first data collection will allow for exploratory analyses of structure and reliability. The second data collection will allow for confirmatory analysis. Expected outcomes include replication of the original multidimensional structure with satisfactory reliability. Although data collection is ongoing, the findings will be presented in forthcoming scientific communication.