This paper explores the efficiency of primary and lower secondary schools in Italy from a productivity perspective. Inputs are related to human and financial resources of schools and outputs represent the achievement in math and reading of their students. The analysis is conducted on a statistical sample of more than a thousand primary and lower secondary schools. We use data envelopment analysis to estimate efficiency and a second-stage model to identify its determinants. Keeping inputs constant, the estimated efficiency distributions indicate there are greater margins of improvement in primary education respect to lower secondary education. In both levels of education, potential productivity gains are particularly large in the South. Factors determining efficiency vary according to the geographical area. A general result is that critical financial management issues have no role in determining efficiency while contextual factors do (despite the fact that the school's average social and economic background is specified in the model as an input). Finally, in the South, being a comprehensive rather than a specialized school can be a factor of inefficiency; this may point out to emerging difficulties in the implementation of legislative provisions directed to rationalizing the school system.