The Sustainable Development Goals highlight the critical importance of pre-primary education and set the broad ambition that by 2030 all girls and boys have access to quality early childhood development, care and pre-primary education so that they are ready for primary education. Today, the world is facing a learning crisis: While millions of children have entered education systems for the first time, many of them cannot read, write or do basic mathematics, even after several years of primary school. This conceptual framework outlines the key building blocks of an effective pre-primary system to ensure children's optimal learning and development in early childhood education programmes.