A significant proportion of pupils move school during their school career for reasons other than standard structural moves between educational stages. Little is known about the underlying causes of these moves and the characteristics and experiences of mobile pupils are challenging to research. This seminar presents analyses of the English National Pupil Database (NPD), tracking a cohort from age 5 to 16, to better understand when school moves occur, the characteristics of mobile pupils and the impact of mobility on attainment. Findings reveal a sizable underlying rate of moves in England of about 1.5–2% per term and identify differences in mobility related to disadvantage, school phase, ethnic group and SEND status. The predictive power of the data for identifying mobile groups, however, is low, highlighting the need for more research, policy and practice in this area to better understand individual mobility circumstances. With regards to attainment, analyses identify moves during the secondary phase – but not the primary phase – as being significantly associated with lower pupil academic progress. This seminar presents results from across these analyses and discusses their implications for policy, practice and further research.