Parliamentary democracy is a system of delegation and accountability that is often misunderstood despite its widespread adoption. This essay identifies the institutional features that define parliamentary democracy and suggests how they can be understood as delegation relationships. Two definitions are proposed: a minimal and a maximal (or ideal-typical) one. The maximal definition suggests that parliamentary democracy is a particular regime of delegation and accountability that can be understood with the help of agency theory, which allows us to identify the conditions under which democratic agency problems may occur. Parliamentarism is simple, indirect, and relies on lessons gradually acquired in the past. Compared to presidentialism, parliamentarism has certain advantages, such as decisional efficiency and the inducements it creates toward effort. On the other hand, parliamentarism also implies disadvantages such as ineffective accountability and a lack of transparency, which may cause informational inefficiencies. Whereas parliamentarism may be particularly suitable for problems of adverse selection, it is a less certain cure for moral hazard. In contemporary advanced societies, parliamentarism is facing the challenges of decaying screening devices and diverted accountabilities. The conventional understanding of parliamentary government includes the ideas of parliamentary supremacy and the notion of fused, or unified, powers. Parliamentary supremacy is the idea that the legislature controls the executive branch and the policy-making process. However, this is not always the case in contemporary parliamentary politics. The role of parliament in drafting legislation and budgets appears to be severely circumscribed. The belief in the unfettered rule by the popularly elected majority lies at the heart of the tradition of parliamentary government. It also implies that the parliamentary front bench is the locus of executive decision making. Moreover, it has been argued that in its pure form, parliamentary democracy means that the members of the core executive must also be members of parliament. Parliamentary supremacy seems strangely at odds with the contemporary realities of parliamentary politics. The critical role of parliament lies not in legislation, but in its role as an electoral chamber. Historically, British parliamentarism emerged simultaneously with the evolution of two cohesive parliamentary parties: a government and an opposition. Over the second half of the nineteenth century, power was increasingly delegated from parliament to the front bench of the majority party, that is to say, the cabinet. The institutional vehicles for the evolution of cabinet dominance were the confidence relationship and the Prime Minister's dissolution power. As a consequence of such delegation, parliaments at least appeared to suffer a political decline. Parliamentary supremacy came to mean extensive delegation to the cabinet, resting on the latter’s threats of resignation and parliamentary dissolution. These threats in turn assumed and implied two-party politics, which has no longer been typical of parliamentary systems since the introduction of proportional representation. In systems without single-member district elections and two-party systems, parliamentarism has taken different and more consensual forms, in which cabinet coalitions are frequent. In many such coalitional systems, the locus of decision making has shifted from the parliamentary front bench to theParliamentary democracy is a system of delegation and accountability that is often misunderstood despite its widespread adoption. This essay identifies the institutional features that define parliamentary democracy and suggests how they can be understood as delegation relationships. Two definitions are proposed: a minimal and a maximal (or ideal-typical) one. The maximal definition suggests that parliamentary democracy is a particular regime of delegation and accountability that can be understood with the help of agency theory, which allows us to identify the conditions under which democratic agency problems may occur. Parliamentarism is simple, indirect, and relies on lessons gradually acquired in the past. Compared to presidentialism, parliamentarism has certain advantages, such as decisional efficiency and the inducements it creates toward effort. On the other hand, parliamentarism also implies disadvantages such as ineffective accountability and a lack of transparency, which may cause informational inefficiencies. Whereas parliamentarism may be particularly suitable for problems of adverse selection, it is a less certain cure for moral hazard. In contemporary advanced societies, parliamentarism is facing the challenges of decaying screening devices and diverted accountabilities. The conventional understanding of parliamentary government includes the ideas of parliamentary supremacy and the notion of fused, or unified, powers. Parliamentary supremacy is the idea that the legislature controls the executive branch and the policy-making process. However, this is not always the case in contemporary parliamentary politics. The role of parliament in drafting legislation and budgets appears to be severely circumscribed. The belief in the unfettered rule by the popularly elected majority lies at the heart of the tradition of parliamentary government. It also implies that the parliamentary front bench is the locus of executive decision making. Moreover, it has been argued that in its pure form, parliamentary democracy means that the members of the core executive must also be members of parliament. Parliamentary supremacy seems strangely at odds with the contemporary realities of parliamentary politics. The critical role of parliament lies not in legislation, but in its role as an electoral chamber. Historically, British parliamentarism emerged simultaneously with the evolution of two cohesive parliamentary parties: a government and an opposition. Over the second half of the nineteenth century, power was increasingly delegated from parliament to the front bench of the majority party, that is to say, the cabinet. The institutional vehicles for the evolution of cabinet dominance were the confidence relationship and the Prime Minister's dissolution power. As a consequence of such delegation, parliaments at least appeared to suffer a political decline. Parliamentary supremacy came to mean extensive delegation to the cabinet, resting on the latter’s threats of resignation and parliamentary dissolution. These threats in turn assumed and implied two-party politics, which has no longer been typical of parliamentary systems since the introduction of proportional representation. In systems without single-member district elections and two-party systems, parliamentarism has taken different and more consensual forms, in which cabinet coalitions are frequent. In many such coalitional systems, the locus of decision making has shifted from the parliamentary front bench to the