At home, he was being treated as a teenager first, @Sweden second.

“Have you had anything to eat yet?” asked his mother, Monica, somewhat sharply (it was nearly lunchtime). Mr. Isberg accepted a piece of bread and took out his cellphone. A photographer snapped his picture.

“Twittering while a photographer runs around trying to take a photo of how I look when I’m Twittering,” Mr. Isberg posted.

The @Sweden program, known as Curators of Sweden, came about when the Swedish Institute and Visit Sweden, the government tourist agency, sought to develop a plan to present the country to the world on Twitter. They hired an advertising company, Volontaire.

“Sweden stands for certain values — being progressive, democratic, creative,” Patrick Kampmann, Volontaire’s creative director, said in an interview. “We believed the best way to prove it was to handle the account in a progressive way and give control of it to ordinary Swedes.”

The @Swedens are nominated by others — people are not supposed to put their own name forward — and then selected by a committee of three, including Mr. Kampmann. The qualifications are that they have to be interesting, Twitter-literate and happy to post in English.

They are told not to do anything criminal, to label political opinions as their own and “not to make it sound like the entire Sweden feels that way,” said Cherin Awad, the Muslim lawyer, who was @Sweden from Feb. 27 to March 4.

Mr. Kampmann says he counsels the @Swedens to engage in “their normal Twitter behavior.”

“I tell them, ‘Please, do this with some dignity — remember that this is an official channel and there are a lot of people reading this, so don’t make a fool of yourself,’ ” he said. “It’s only a soft suggestion.”