Low achievement among children who frequently change primary schools is often due to factors other than mobility, a report shows.
Researchers have found little evidence to show that high mobility affects performance. Rather, they believe it is to do with learning and social difficulties, having English as a second language and a low academic starting point.
A study from Warwick university and the London borough of Lambeth looked at the achievements of 2,279 pupils from 59 primary schools who completed key stage 2 tests in summer 2002, together with data on their prior attainment at key stage 1 and other background information.
Of the sample, 779 pupils - or 34.2 per cent - had changed schools at least once during the course of KS2. Two-thirds had completed KS1 tests and joined from other schools in England. Just over 11 per cent entered the UK from abroad.
The study, published in the British Educational Research Journal, found that while 75 per cent of the "stable" cohort had achieved level 4 or above in KS2 English, the figure for mobile pupils was 59 per cent.
Almost three-quarters, 74 per cent, of pupils who had remained in the same school achieved level 4 in maths and 88 per cent in science. Among mobile pupils the figures were 58 per cent and 74 per cent respectively.
The backgrounds of the mobile pupils revealed factors that might have caused the pupil to have to change schools.
The report, Pupil mobility, attainment and progress in primary school, by Steve Strand and Feyisa Demie, said: "A key factor in understanding the relationship between mobility and attainment is the reason for mobility.
"One-third of mobile pupils had arrived from school outside England, often as refugees, asylum seekers or economic migrants, and these pupils accounted for the major part of the effect ascribed to pupil mobility.
"The low attainment is the result not of changing school but of a broad range of factors including substantial cultural, educational and social adjustment."
However, this did not mean that mobility was unimportant, the authors concluded.
"Irrespective of the effect of pupil mobility on attainment, there are significant resource implications for the effective management of mobility in the school and classroom," they said.
"Substantial time has to be spent on enrolment, assessment, obtaining records, arranging SEN or language support, getting to know the parents and child, integrating the new pupil and fostering a feeling of class identity.
"Schools with high levels of pupil mobility need to be resourced to meet this challenge."