Lots of voting, low turnout
National elections to choose the 200 lawmakers who sit in the lower house and 46 senators are held every four years.
But Swiss voters also have the chance to express themselves multiple times a year through the country's direct democracy system.
Any initiative to modify the constitution that gathers 100,000 signatures is put to a popular vote, while 50,000 signatures are enough to call a referendum opposing a law voted by parliament.
The last time turnout passed 50 percent in parliamentary elections was 1975. But voter participation on popular initiatives or referendums can be higher when the issues on the ballot capture public attention.
Sunday's vote will decide the new parliament, but the executive branch, or Federal Council, will not be in place until December.
Under a tacit, decades-old agreement dubbed the “magic formula”, the seven ministerial posts in the executive branch are shared among Switzerland's major parties.
The system ensures that the cabinet reflects views from across the political spectrum and the executive has generally remained unaffected by power-balance shifts in parliament.
Since its introduction in 1959, the formula maintained an identical government composition until 2003.
That year, the anti-immigration right-wing Swiss People's Party (SVP) demanded an additional seat to reflect its surging popularity.
Now the Federal Council counts two SVP representatives, two from the Socialist Party, two from the right-leaning Free Democratic Party and one from the centrist Christian Democrats.
Polls show that an alliance of parties that support bold action to address climate change could force their way into the council, in what would be a major pivot for Swiss governance.
Regardless of the makeup of the new national parliament, Switzerland's 26 cantonal governments will continue to retain substantial authority. Each canton has its policies for education, religion, and police matters.
The cantons share decision-making with Bern on taxes, the judiciary, economy, social benefits and foreign policy.