Although school psychologists are involved in dealing with the problem of pupil absenteeism at both the individual child and whole school level, one of the possible reasons for their involvement, namely the belief that significant absence from school has an effect on attainments, is actually founded on weak evidence. The literature review presented in this article revealed that, in order to determine the effect of absence on attainments, no satisfactory study had hitherto been conducted in which attainments had been measured before and after a period of absence. However, the results of longitudinal research partially conducted by the present author, reported in this article, do show that absence from school has a significant effect on primary school attainments. In particular, it was found that an absence of half a year between the ages of 7- and 11-years-of-age resulted in a reduction of 0.7 of a year and 1 year in reading and mathematics test scores respectively. The article ends with a consideration of the kind of research which still needs to be conducted in order to provide school psychologists with the information they need to deal successfully with pupil absenteeism problems. (Contains 3 tables.)