How is upper secondary education organised across OECD countries? This level of education, which most frequently serves students aged between 15 to 18, is generally the first time when learners have significant capacity to shape the content of their learning, for example by opting for general or vocational education, choosing their subjects and developing a specialisation. Across the OECD, education systems have developed different ways to be responsive to different student needs and interests while trying to ensure that learners develop coherent foundational skills. This paper captures the diversity of countries' upper secondary systems by: (1) developing a common language that sets the foundation for internationally comparative analysis; (2) categorising how countries organise their programmes in upper secondary education to manage choice, coherence and specialisation; and (3) identifying benefits and strategies to mitigate the risks associated with different approaches to upper secondary programmes for students, education systems and society.