The EPPE 3-11 Project builds on the work of the earlier Effective Provision of Pre-School Education (EPPE) project, which was the first major longitudinal study in Europe to investigate the impact of pre-school provision on a national sample of young children, tracing their development between the ages of 3 and 7 years. EPPE 3-11 follows the same sample of 2500 plus children to age 11 years, the end of Key Stage 2 (KS2). This research brief reports the results of detailed observations of practice conducted in 125 Year 5 classes attended by EPPE children, and measures the variation in teachers' organisation and pedagogy and in pupils' responses. The brief describes patterns of association between indicators of primary school effectiveness (measured using value added approaches and national assessment results) and quality (measured by Ofsted inspection grades) and differences between Year 5 classes in observed practice and behaviour. The observations were conducted in a range of lessons with a particular emphasis on the core subjects.