It is well recognised that the grazing behaviour of sheep is influenced by the availability of vegetation (Hodgson, 1985). However, the extent to which grazing may also be influenced by social factors related to stocking density is not well understood, since stocking density and herbage availability are normally confounded. In this study an experimental design was used which, for the first time, allowed the effect of stocking density on grazing behaviour to be explored without being confounded with differences in herbage height or mass.