Recently, students of European parties have come to agree that organizational power has been concentrating in the party in public office (PPO), whose particular interests and objectives shape those of the party at large. This process of growing autonomy of the PPO—hypothesized by Katz and Mair—goes hand in hand with that of party penetration of the state and with a corresponding decline of party presence within civil society. This chapter aims to verify, empirically, if the PPO is indeed moving in the direction of becoming the strongest party organizational ‘face’. It also investigates whether the degree of ascendancy of the PPO varies 1) across parties and 2) across countries. To this end, it analyses persistence and change in party organizations across ten European countries, from the 1970s to 2010, using data from the Political Party Database Project (PPDB) and comparable data from the Party Organizations Data Handbook.