Even though Prime Ministers (PMs) are the central actors in parliamentary democracies, to date little comparative research aims to explain their performance in office. This article explores whether and why certain PMs perform better than others. For that purpose, we make use of a unique expert survey covering 131 cabinets in eleven Central and Eastern European countries between 1990 and 2018. Performance is defined as a two-dimensional set of tasks PMs ought to fulfill: first, managing the cabinet and directing domestic affairs as tasks delegated to their office, second, ensuring support of parliament and their own party, who constitute the direct principals. Our findings indicate that former political involvement provides heads of governments with political experience which enhances their likelihood to fulfill their tasks as PM successfully. In particular, heads of government who served as party leaders have the best preconditions to succeed in office.