In the evaluation of any political strategy, it is essential to carry out the collection and analysis of the available data. The presentation of a complex phenomenon by means of synthetic measures can improve both the political actors' understanding of the situation and the design of new measures. In this paper, we deal with the problem of the construction of a multidimensional composite indicator for the evaluation of educational systems in OECD countries. In our proposal, not only are those indicators included that measure the academic outcomes, but also a group of indicators that measures the social dimension of the educational system. A variation of a methodology based on Data Envelopment Analysis is developed to construct a composite multiplicative indicator that enables inter-temporal comparison and the detection of the sources of the variation.