This research is based on an empirical study conducted in two Teacher Education Institutions (the IUFM) and in secondary schools in the Paris area. It investigates the sociopedagogical and institutional issues at stake in the increased emphasis on school experience and school-based training in initial teacher education, which have led to the development of new professional roles and relationships aiming at building bridges between initial teacher education institutions, schools and practitioners. This evolution has favoured the renewal of the influence of supervising staff, whose role and status tend to differenciate and become more complex. Based on semi-structured interviews conducted with the main actors of teachers’ training – students’ mentors in schools, associate professors in the IUFM, training coordinators, student teachers themselves – this study aims at clarifying, from the actors viewpoints, the partnership adopted between the training institutions and the schools as well as the training, tutoring and mentoring schemes in place, and at examining the evolution of teachers’ educators and mentors roles and student teachers/mentors/educators relationships in practice.