This paper describes how a group of primary schools in Northern Ireland planned a differentiated curriculum, and the extent to which subject co-ordinators offer guidance to teacher colleagues in planning for English, mathematics and science. The views of headteachers, subject co-ordinators and teachers on the ways in which plans are translated into classroom practice for higher and lower attaining pupils in both classwork and homework were obtained. The curriculum support staff described how far they consider teachers are applying the principles of differentiation, including progression and continuity. The results showed that, although most teachers were said to understand the meaning of differentiation moderately well, help was needed in drawing up schemes of work and providing for the extremes of pupil attainment.