Do teachers spend more time on actual teaching and learning in a typical lesson compared to previous years? Do they feel prepared to teach when they start teaching? What sort of continuous professional development programmes do they participate in and how does it impact their practice? This report looks first at how teachers apply their knowledge and skills in the classroom in the form of teaching practices, with an accompanying assessment of the demographic makeup of those classrooms and the school climate to provide context on learning environments. The volume then assesses the ways in which teachers acquired their knowledge and skills during their early education and training, as well as the steps they take to develop them through continuous professional development over the course of their career. Based on the voice of teachers and school leaders, the report offers a series of policy orientations to help strengthen the knowledge and skills of the teaching workforce to support its professionalism. 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.