Previous research has found mixed evidence regarding the change of parliamentary voting behaviour following electoral reforms. But scholars have not analysed whether the mechanisms by which voting loyalty is elicited matter differently in such cases. Our article fills this gap by investigating the individual variation in voting loyalty across two legislative terms, using a sample of 26 high-stakes roll-call votes. Romania constitutes an ideal setting for such a study due to its recent shift from closed-list proportional representation to single-member districts. Multivariate ordinary least squares models (including all Members of Parliament and including only incumbents) test for the effect of parliamentary experience, party membership duration, parliamentary office, party hopping and district magnitude, while also accounting for demotion and a number of socio-demographic controls. Results indicate that socialisation is less important for Members of Parliament’s voting behaviour after reform, whereas signalling through voting dissent prior to party switching becomes more relevant.