This paper discusses the teaching and assessment of 21st century skills and competencies in OECD countries, based on a questionnaire study and other relevant background materials. It presents a discussion of the importance and relevance of these skills in current policy debates, along with definitions and conceptual frameworks used in the literature. A new three-dimensional framework is proposed, consisting of the dimensions of information, communication, and ethics and social impact. The findings of the questionnaire show that most countries or regions cover 21st century skills and competencies in their regulations, guidelines, or recommendations for compulsory education. However, there are few specific definitions of these skills and competencies at national or regional levels, and virtually no clear formative or summative assessment policies for these skills. The only evaluation regarding their teaching is often left to external inspectors as part of their whole school audits. Similarly, there are few teacher training programmes that target the teaching or development of 21st century skills, although there exist several teacher training initiatives that focus on developing teachers' ICT pedagogical skills, most of them optional. The paper discusses the implications of these findings, especially regarding the particular role of ICT in the development of these skills and competencies, and issues related to assessment practices and teacher training. It also highlights the importance of defining these skills and competencies clearly and developing policies that support their teaching and assessment. The paper concludes that while many OECD countries have begun to incorporate 21st century skills into their education systems, there is a need for more consistent and comprehensive approaches to ensure that these skills are effectively taught and assessed.This paper discusses the teaching and assessment of 21st century skills and competencies in OECD countries, based on a questionnaire study and other relevant background materials. It presents a discussion of the importance and relevance of these skills in current policy debates, along with definitions and conceptual frameworks used in the literature. A new three-dimensional framework is proposed, consisting of the dimensions of information, communication, and ethics and social impact. The findings of the questionnaire show that most countries or regions cover 21st century skills and competencies in their regulations, guidelines, or recommendations for compulsory education. However, there are few specific definitions of these skills and competencies at national or regional levels, and virtually no clear formative or summative assessment policies for these skills. The only evaluation regarding their teaching is often left to external inspectors as part of their whole school audits. Similarly, there are few teacher training programmes that target the teaching or development of 21st century skills, although there exist several teacher training initiatives that focus on developing teachers' ICT pedagogical skills, most of them optional. The paper discusses the implications of these findings, especially regarding the particular role of ICT in the development of these skills and competencies, and issues related to assessment practices and teacher training. It also highlights the importance of defining these skills and competencies clearly and developing policies that support their teaching and assessment. The paper concludes that while many OECD countries have begun to incorporate 21st century skills into their education systems, there is a need for more consistent and comprehensive approaches to ensure that these skills are effectively taught and assessed.