The European Commission employs over 22,000 officials who see to the administration of the European Union. In 2003 the Commission introduced a performance appraisal and promotion system based on points earned each year. After about five years of operation it became clear that this system was not satisfactory and needed to be revised. A team from Lancaster University worked closely with Commission officials to develop a simulation model, which is used to demonstrate the performance of the current system and to show how alternative systems might function. As a consequence, the various stakeholders in the Commission's performance appraisal and promotions system have agreed to implement an improved system in 2009. The simulation model is unusual in the field of manpower planning because of the requirement to model the consequences of appraisal system rules. It also uses novel regression-based sampling schemes which prove to be both accurate and efficient. Finally the role of the model in scenario exploration and system redesign is discussed.