Each canton has its own parliament. The Confederation does not lay down any regulations on how the day-to-day running of these parliaments should be organised – the Federal Constitution does, however, require that they are democratically elected. In contrast to the governments, the cantonal parliaments, despite the increasing complexity of their tasks, are rarely made up of professional members: cantonal politics at the level of the legislature is part-time work. The cantonal parliaments do not normally play a dominant role in the system of cantonal institutions. They are not able to elect the government and, due to the wide-ranging instruments of the direct democracy, they rarely have the final say on proposed legislation.

Although their general set-up is relatively uniform, there are major differences between the cantonal parliaments, mainly in relation to their size, the electoral systems, the funding of parties and the parliamentary infrastructure. Normally the larger cantons have rather larger parliaments, but the determining factor is not the size of the population. Some cantonal parliaments meet in sessions lasting for several days, others meet regularly for one day, half a day, or in the evening. The cantonal parliaments also have committees in which business is discussed behind closed doors and then passed on to the full parliamentary meeting. The importance of the parliamentary committees varies from canton to canton (standing and non-standing committees). Only a very few cantons have an independent parliamentary service that is separate from the rest of the cantonal administration. In recent years, some cantons have reduced the number of seats in their parliament. This now ranges among the cantons from 46 to 180 seats.

Most cantons elect their parliaments by a system of proportional representation. For the purpose of these elections, the cantons are divided into constituencies, which are normally based on district, or in some cases communal boundaries.