This paper examines the causes of pupil mobility and good practice in schools to address mobility issues. Pupil mobility is defined as 'a child joining or leaving school at a point other than the normal age at which children start or finish their education at that school'. The first part draws upon evidence of a survey, which explores the views of headteachers on the nature and causes of pupil mobility in schools and the priority they give to addressing pupil mobility issues in their schools. It examines the cause of mobility in schools in the context of mobile groups. This is followed by the challenges for managing mobility and strategies to address pupil mobility in schools. The second part of the paper outlines successful strategies that minimize the effects of mobility in schools. Evidence is drawn from case-study research and focuses on the school systems, pastoral care and access to learning which combine to support the induction, assessment and monitoring of newly arrived pupils in school and effective use of data for self-evaluation. Examples of flexible curriculum organization, innovative approaches to additional support and effective administrative procedures are drawn upon. Evidence reflects the views of a range of school staff, parents/carers and pupils in the case-study school, as well as the judgements of senior researchers. Policy implications for government and for all concerned with school performance are highlighted, as well as many practical suggestions for raising achievement of mobile pupils