The systemic turn deliberative theorists of democracy have taken in recent years marks an important insight: that legitimacy claims are to be directed at the political system as such and not at individual actors and forums within it. Its proponents have argued that deliberative systems can and have to include deliberative and non-deliberative forms of interaction and decision-making. What matters is that these, too, are deliberatively justified and contribute to the deliberative and democratic qualities of the system as such. In this light, even high-quality elite deliberation or perfect mini-publics might not enhance the overall quality of democracy. In fact, the systemic approach can also have conservative implications if it justifies deficient institutions and decision-making procedures by arguing that they somehow contribute to the deliberative or democratic quality of the system. Our paper contents that deliberative democracy after the systemic turn remains institutionally underdetermined. In particular, it still needs to identify constellations of representative institutions that enable both effective citizen participation and inclusive deliberation. Drawing on four case studies (United States, Germany, Switzerland and Ireland), we argue that deliberation needs to be “plugged in” both at the citizens’ side and at political elites and decision-makers’ side. We identify combinations of institutional parameters – focussing on electoral systems and varieties of bicameralism – that have the potential to ensure that deliberation is plugged into a representative system and realizes its potential for both rational decision-making and effective participation.