On 26 October 2017, the Italian Parliament approved a new electoral system nicknamed Rosatellum after Ettore Rosato, head of the Partito Democratico’s (PD, Democratic Party) parliamentary group in the Chamber, who was the first proponent of the law. The new electoral system is the fourth since 1993. It is a mixed system, like the others, and it applies to both the Chamber and the Senate. Roughly two thirds of the seats are assigned with a proportional formula in multi-member districts. The remaining seats are assigned in single-member districts with plurality rule. The impact of the new electoral system in terms of party representation has been more proportional than majoritarian. No party or coalition won an absolute majority of seats. However, if we look at its overall per- formance the picture is mixed. After all, the SMDs are a potent tool and they have made the difference in terms of voting behaviour and pattern of competition. Two pre-electoral coalitions have been formed, the centre-left and the centre-right, which presented themselves, along with M5S, as potential government alternatives. The agreements made among their members acted as a constraint on possible post-electoral alliances making diffi- cult to form a government. This is one of the main reasons of the long stalemate.