There has been little research on pupils' experiences of ability grouping. This study aimed to explore the perceptions of primary-aged pupils regarding the purpose and practice of within and between class ability grouping; their experiences of those practices; and how their attitudes to school, self-perceptions and behaviour were affected. The study was undertaken in six primary schools adopting different combinations of grouping practices including streaming, setting, within-class ability and mixed ability grouping. Six pupils, of high, moderate or low ability, mixed in gender, in each Key Stage 2 class were interviewed in each school. The findings showed that pupils were aware of how and why they were grouped and accepted the rationales provided. Attitudes towards school were not affected by grouping structures, but pupils' awareness of their place in the pecking order and the nature of teasing in the school were, although these were mediated by school ethos factors.