Understanding teachers and school leaders as "professionals" means having high expectations of them as advanced knowledge workers. It means they should not only conduct their work in an effective manner, but also strive to improve their skills throughout their career, collaborate with colleagues and parents to work towards school improvement, and think creatively about the challenges they face. However, if we expect teachers and schools leaders to act as professionals, we should treat them as such. This report aims to provide an in-depth analysis of teachers' and school leaders' perceptions of the value of their profession, their work-related well-being and stress, and their satisfaction with their working conditions. It also offers a description of teachers' and school leaders' contractual arrangements, opportunities to engage in professional tasks such as collaborative teamwork, autonomous decision making, and leadership practices. Based on the voice of teachers and school leaders, the report offers a series of policy recommendations to help strengthen the professionalisation of teaching careers. The OECD Teaching and Learning International Survey (TALIS) is the largest international survey asking teachers and school leaders about their working conditions and learning environments, and provides a barometer of the profession every five years. Results from the 2018 cycle explore and examine the various dimensions of teacher and school leader professionalism across education systems.