Since the 19th century, a lively interest in the history of representative institutions has led to a great number of source editions and monographies, and an impressive series of prosopographical data, but there is an evident lack of systematic, comparative analyses. Moreover, the focus has primarily been on institutional aspects and less on the social and economic embedding of the political agency. This article argues that too little is known about the routine functioning of representation and its evolution over the centuries. It matters if the landed aristocracy is dominant within a polity, or if there are countervailing powers, especially from commercial cities. The variety in the structures, the concrete functioning, agenda, impact and the representatives’ social background can be understood in their relation to the most dynamic classes in the particular political community. State budgets were mostly determined by expenses for dynastic warfare and for the public debt, while merchant classes generally aimed at free trade and low interest rates. This paradox may be elucidated by looking at the delegates’ and their principals’ personal position and interests. The institutional evolution tends to oligarchisation, inertia and shifting away from the initial goals.