One of the aims of the national agenda for education is to foster the achievement of Australian students in key learning areas such as numeracy and literacy. A central question, in this context, is at which level resources should best be allocated in order to maximize their effect on improving learning outcomes. Put differently, the question is whether it is more effective to direct resources to schools, their staff and infrastructure or to students and their families. To address this question, the South Australian Department of Education and Children Services (DECS) commissioned the Australian Council for Educational Research (ACER) in April 2009 to undertake: a) multilevel analyses of the Australian PISA assessments for Australia overall in 2000, 2003 and 2006 and by State and Territories for 2006; and b) a literature review of published studies that have reported multilevel analyses aimed at mapping and explaining differences in achievement between students within schools and between schools. Results of these analyses are summarized below. First, findings are presented regarding the proportioning of differences in achievement that can be attributed to the student and the school level. Second, results of a review of published results of factors explaining those differences are provided.