The paper aims at presenting a Performance Measurement System (PMS) developed in an Italian project, performed by the authors within a Nonprofit Service Organization (NSO). Like profit organizations, nonprofit ones must measure their performances, in order to define possible improvements. The paper proposes a PMS, derived from the well known Balanced Scorecard approach, specifically dedicated to NSOs. In particular, a case study has been conducted within an Italian NSO, active in the construction sector, located in the Northern Italy, in the county of Bergamo.