How do parties that have long been confined to opposition behave once they take the decision to support government? This article analyses the case of the three Portuguese radical left parties that took such a move in the wake of the post-bailout 2015 election. Leveraging the concept of contract parliamentarism and the analysis of different data sources through different methods, we show that the three parties adopted a similar strategy after agreeing deals with the centre-left socialists. Specifically, while keeping close scrutiny on the executive action, the parties have voted consensually on most of the legislation proposed by the government. In exchange, the majority of policy pledges agreed with the socialists were implemented by the beginning of the legislature. Based on these findings, the article underlines the importance for supporting parties of conducting a thorough negotiation of policy goals and the timing of their implementation before joining the government, and of pursuing an autonomous discursive agenda.