Party affiliation is generally considered as a long-lasting choice. This tends to be particularly true for MPs, whose career normally evolves within a single party. Therefore, legislative party switching is relatively rare in most democratic systems. This is not the case for the Italian Parliament where party switching is a common phenomenon. Consequently, it is not surprising that party switching in the Italian Parliament attracted the attention of several scholars who focused in particular on Legislature XIII (1996-2001) when party switching had a strong impact on the making and breaking of governments. This phenomenon has seen a revival during Legislature XVI (2008- ) when the Berlusconi government was replaced by a non-partisan administration. Using a new dataset with information on the duration of MPs’ party affiliation in the Italian Lower Chamber from 1996 to 2011 (i.e. the end of Berlusconi government) this paper aims to explain why some legislators are more loyal to their parties, while others decide to leave and switch (sometimes more than once) party. Focusing on Italy as a case study, this paper will test a general model of the determinants of party switching using survival data.
