This paper addresses one of the key challenges for work on education, sustainable development and climate change: the overall conceptualisation of central ideas such as Environmental Education (EE), Education for Sustainable Development (ESD) and Climate Change Education (CCE). What do these concepts mean in diverse contexts and amongst diverse actors? The paper draws on evidence from Denmark, Singapore, Canada and the UK to highlight both the similarities and differences found within national discussions around these essentially contested concepts and their relationships to policy and practice. It further argues that such debates about how EE, ESD and CCE are conceptualised remain highly relevant, not just to academic work itself, but also to wider international discussions regarding both the current and potential relationships between conceptual understanding, policy and practice. (Contains 2 notes.)