This book explores how power-sharing between the president and the prime minister works in semi-presidential regimes. In contrast to much of the existing comparative work on semi-presidentialism, the book emphasizes the role of institutional coordination at the most concrete level of executive policy-making, and asks how institutional coordination between the president and prime minister influences presidential activism and the balance of power within the executive. The authors develop a tentative framework embedded in institutionalism and based on four strands of research – semi-presidentialism, public administration, political leadership, and foreign policy analysis – which is subsequently applied to the cases of Lithuania, Romania and Finland. Given the political challenges facing many semi-presidential countries, the study ultimately seeks to identify institutional solutions that facilitate power-sharing and successful policy-making.