Nowadays, despite widespread recognition of the importance of performance measurement systems (PMSs), there are some issues that require further investigations if PMSs are to be e.ective in their role of control support. This article seeks to illustrate that the Choquet integral aggregation operators can address the problem of taking interactions between performance criteria into account. But the use of this quite complex approach requires to explicitly de.ne pieces of information aimed at aiding decision makers by a better understanding of the contribution of the elementary performances to the overall one, and at better assessing the di.erent ways of improving the overall performance. In this view, indexes of e.cacy and e.ciency of the elementary performances aggregated by a 2-additive Choquet integral are proposed and applied to a case submitted by a small and medium-sized company (SME).