Built on concurrent claims of legitimacy, the semi-presidential constitutional framework is prone to conflicts between the office holders. Cohabitation is a particular instance in which the president’s party is not represented in government and he has to share executive power with a prime minister. Instead of producing a flexible dual-authority structure within the executive, cohabitation has always tended to generate institutional crises in Romania, ending with the impeachment of the president (2007 and 2012). This article identifies a combination of four factors leading to this outcome: legislative ambiguity, the composition of the legislature, the absence of external pressures, and the leaders’ personality.