Parties are not unitary actors, and legislators within the same party may have divergent interests, which complicates the understanding of parties’ motivations and behaviour. This article argues that holding a ministerial portfolio confers an electoral advantage, and so, in contrast to their co-partisans, politicians who are ministers simultaneously maximize policy, office and votes. New data on Irish elections over a thirty-year period show that ministers are insulated from the electoral cost of governing compared with their co-partisans. Differentiating between ministers and their co-partisans helps to resolve the puzzle of political parties’ choosing to enter government despite the evident electoral costs they will encounter. Moreover, previously overlooked electoral benefits of ministerial office help explain their desirability, and thus their ability to incentivize legislative behaviour in parliamentary regimes.