The activity-based costing, applied in public services, is a full costing method which recognizes the relationship between costs, activities, and products/services of a public administration. The ABC has the function to support the decision-making process and to inform the management about the resources acquisition and the level of resources utilization. In fact, a cost accounting system aims to provide an organization with relevant cost information, related to product and services, to support the decision-making process. Traditionally, the cost accounting system of an organization was designed to support the needs of financial (external) reporting and to help the determination of a satisfactory price for goods and services sold. When traditional methodology has been developed, direct labor and materials were the most significant product or service costs, with overhead costs that engraved only with a small percentage of total costs. In the recent context of the public administration corporatization and of the outsourcing processes for the public services delivery, the awareness that the resources are becoming increasingly scarce and, therefore, that it is necessary to use them in a cost-efficient way, in order to achieve high standards, plays a pivotal role. Therefore, with reference to the public service sector, the ABC verifies, for each service, the acquired financial resources, the costs of each productive factor, the obtained qualitative and quantitative results, and the revenues.