Addressing the quality challenge is intended to support the discussion within National Commissions, UNESCO and its member states by clarifying the concept of educational quality. Policymakers and other education professionals around the globe are invited to use this paper to shape their thinking on the concept of quality in the post-2015 education agenda. Quality is important and part of a bigger picture: it starts with accessibility to education, but educational relevance with a view to the future is also important. In the end, education should prepare people for life and work. The exploration is based on the education quality framework of the Netherlands Institute for Curriculum Development (SLO). This framework is used in this paper to interpret the needs and wishes arising from the post-2015 education agenda. Each following section will start with a definition of the problem, followed by an exploration of the relevant conceptual and more substantive principles. The resulting methodological and strategic suggestions should be addressed at the national and local level. Each exploration wraps up with a set of pointers for future action at the national level.