A new OECD report, Supporting Teacher Professionalism, based on the Teaching and Learning International Survey (TALIS), conceptualises teacher professionalism as being comprised of: knowledge base, defined as necessary knowledge for teaching; autonomy, defined as teachers’ decision-making over aspects related to their work; and peer networks, defined as opportunities for information exchange and support needed to maintain high standards of teaching. Education systems differ in terms of the emphasis placed on each of the teacher professionalism domains. Across all systems there is a particularly positive relationship between knowledge and peer network domains and teacher satisfaction, self-efficacy and perceptions of the value of the teaching profession in the society. Practices supporting teacher professionalism are less common in schools with higher proportions of socio-economically disadvantaged students. However, investing in teacher professionalism can be particularly beneficial in these schools as the positive relationship between knowledge, peer networks and teacher satisfaction is amplified in challenging schools.