The responsiveness to societal demands is both the key virtue and the key problem of modern democracies. On the one hand, responsiveness is a central cornerstone of democratic legitimacy. On the other hand, responsiveness inevitably entails policy accumulation. While policy accumulation often positively reflects modernisation and human progress, it also undermines democratic government in three main ways. First, policy accumulation renders policy content increasingly complex, which crowds out policy substance from public debates and leads to an increasingly unhealthy discursive prioritisation of politics over policy. Secondly, policy accumulation comes with aggravating implementation deficits, as it produces administrative backlogs and incentivises selective implementation. Finally, policy accumulation undermines the pursuit of evidence-based public policy, because it threatens our ability to evaluate the increasingly complex interactions within growing policy mixes. The authors argue that the stability of democratic systems will crucially depend on their ability to make policy accumulation more sustainable.