With the white-clad Band of the Royal Swedish Navy standing to attention beside him, the parliament's Speaker, Per Westerberg, says "Today we celebrate ourselves, and each other, regardless of political views, age, background, or wherever we may live."
So far this year over 16,000 people have become Swedish citizens. Mostly people who already had citizenship from Iraq: 6,000, and far fewer from Poland and Thailand, less than a thousand in both cases.
The third biggest group is people who previously had no citizenship at all - stateless people - which underlines that Swedish immigration is largely about offering protection to people who are fleeing wars and chaos in the places where they grew up.
At the ceremony, Parliament speaker Per Westerberg describes what he sees as some important characteristics of Sweden.
He says, Sweden is "unique" in having had two hundred years of peace, and this is a day to remember that achievement. Plus, he talks of all the rights that citizens have here, rights that were written into the constitution just over two hundred years ago. Things like "freedom of the press, the right to own property are some of the oldest", he says.
Back then, very few of Sweden's citizens could have a say - the right for all adults to vote didn't come until 1921. And Per Westerberg goes on to say that it is every citizen's duty to get involved, since they can now vote and maybe even get elected to the parliament.
So what does this new citizenship mean to the people who have just been welcomed to Sweden. After Per Westerberg finished, the flags outside the parliament were hoisted by two new Swedes, and when Radio Sweden asked one of them what he thought, we got a surprising answer.
Khalid al-Awani says that while it is "an incredible feeling" to become a citizen of another country, he doesn't believe in dividing up the world with national borders. He says that now, in 2013, everyone should be able to live "wherever they like". He says "Sweden, Somalia, Iraq - it doesn't matter". Khalid al-Awani himself has previously had Iraqi citizenship.