Results from the SACMEQ study have the potential to influence policy reform in systems of education in developing countries and may be shaping the development of education in Seychelles. In this paper, specific results of the distribution of pupil achievement scores in reading and mathematics from fourteen countries participating in the SACMEQ II Project have been analysed to investigate sources of variation. The large variation in the context of Seychelles has been related to the selective effect of ability streaming in the primary school system in Seychelles. Through a description of the persistent nature of this practice some of the equity problems, in terms of learning outcome, teaching learning environment and gender disparity, associated with it have been identified. The ways in which cross-country comparisons of the magnitude and source of variation can be used to situate and clarify the country-specific issue of streaming have been explained. By considering the links that could be developed between international and national research and reform measures in the education system Seychelles an interactive process of policy reform which includes information dissemination, policy dialogue and policy action have been discussed.