This study explored the ways in which schools addressed the needs of pupils in low-attainment class groups, or sets, in the context of multiple and contrary government policy directives and inconclusive research findings about setting. In this article we have focused on school and classroom practices as well as the organisational processes through which low-attaining pupils were identified, grouped and reviewed within schools. The empirical data reported here predominantly refer to case studies involving classroom observations and interviews with teachers, pupils and other staff in 13 schools--both primary and secondary--from four local authorities (LAs). In the latter part of the article, however, we also draw on survey data collected from a larger sample of schools in 12 LAs in England. Although the study found ample evidence of innovative school practices and efforts by individual teachers aimed at optimising the learning opportunities for children in low-attainment class groups, the findings also raise important questions about some of the processes of set allocation, the lack of mobility between sets, and the over-representation of particular social groups in low-attainment classes. We conclude with a discussion of the implications for equity and inclusion that moves beyond an emphasis on classroom practice to include questions about the in-school processes of social selection and educational mobility for pupils identified as low-attaining. (Contains 3 tables.)