Since the introduction of the Child Friendly School (CFS) Policy, Cambodia`s educational system has experienced a wave of reforms that aim at raising the quality of education. This is closely linked to twenty-first century approaches for children´s holistic development. For teaching professionals this means engaging with a new teaching approach. In this learner-centered paradigm, teachers become facilitators of learning where knowledge is constructed by the learner rather than recited from a teacher-fronted lesson. Although this is meant to shape a new understanding of the teachers´ professional role, it raises challenges at the same time. Teachers are now expected to embrace these new approaches, which is, however, likely to collide with long-standing structures in teacher education and deeply ingrained teaching practices. This paper aims at discussing the new requirements set by UNICEF´s CFS with regard to the current state of teacher professionalization in Cambodia, taking into account the country´s historical and environmental background. In the context of the CONTESSA project, this contribution not only explores the nature of the CFS Policy, but it also argues its critical reception by teaching professionals and the need for finding sustainable education programs that help foster teachers´ continuous professional development, as for instance achieved by international cooperation such as in capacity building projects.