School counsellors provide professional assistance to ensure the positive mental development of children and adolescents on campus. In this study we adopted the Delphi technique to clearly identify the professional competencies needed by qualified full-time counselling teachers in Taiwan. Using the responses of 21 experts, a framework of 39 competencies covering five domains was developed: self-awareness and professional development, constructing and supporting guidance work, school-based guidance work, client-based guidance work, and system connection and collaboration.