Shared Service Centers are widely used in corporate practice. However, their high practical relevance is contrasted by a weak conceptual foundation. Furthermore, the controlling of Shared Service Centers has only been sporadically addressed in the literature. Against this backdrop, this work provides a theoretical foundation for the Shared Service Center concept and develops a comprehensive controlling toolkit that explicitly takes into account the specific characteristics of such organizational units. The theoretical findings were validated through an empirical study conducted in German companies.