This paper discusses issues related to the teaching and assessment of 21st century skills and competencies in OECD countries drawing on the findings of a questionnaire study and other relevant background material such as white papers or curriculum documents. Although all OECD countries were invited to participate in the questionnaire survey, responses were received from seventeen countries or regions, and the paper focuses primarily on this group. The paper presents a short discussion of the importance and relevance of 21st century skills and competencies in the current policy debate and the definitions and conceptual frameworks that have been used in the literature, and proposes a new three-dimensional framework, consisting of the dimensions of information, communication and ethics and social impact. The findings of the questionnaire survey 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 level 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 with regard to the particular role of ICT in the development of these skills and competencies, and issues related to assessment practices and teacher training.