Developing, promoting and maintaining a good professional teaching workforce from primary to upper secondary education is a policy imperative for education systems around the world. The data drawn from the OECD Teaching and Learning International Survey (TALIS) can help policy makers and education practitioners design policies and practices that enhance teaching across education levels. This report presents TALIS 2018 findings for countries and economies that took part in the primary and upper secondary education survey. It focuses on the following research questions: What are the levels of teachers’ and school leaders’ professionalism in primary and upper secondary education? What are some of the educational challenges unique to each education level? What are the factors that could explain differences in the levels of professionalism across education levels? The findings offer a broader view of teachers and school principals across all levels of compulsory education and the similarities and differences in the issues they face. The report also offers policy reflections on these findings.