The protesters said they were taking a stand against the war in Afghanistan. They gathered downtown Monday morning at the building that houses President Barack Obama's campaign headquarters.
After singing songs of peace outside, the demonstrators, part of a group called Catholic Workers, moved inside the Prudential building.
Catholic Workers launched what organizers call a "Week Without Capitalism" in protest of the upcoming NATO Summit. They are calling for more money to be spent on helping the poor and less on war.
Once in the lobby, the protesters requested a meeting with the president's staff to encourage a complete withdrawal from Afghanistan, but security guards shut down the elevator banks, and approximately 30 Chicago police bike officers responded within minutes. The protesters read a statement and were arrested when they refused to leave after reading the statement.
Six men and two women were led out of the Prudential building in handcuffs for trespassing.
"Now I can get back to work and get working for the cause to stop NATO this week," said Sam Yergler, one of the arrested protesters who was free by Monday evening.
"We see NATO as an egregious act of violence and oppression. As Catholics, we believe in the works of mercy, that it is important to build community," said protester Jerica Arntz.
"In a symbolic way, we have sent out our message to the Obama campaign and to media outlets around the city to say we can live without NATO," said Jake Olzen, also a protester.
With the NATO Summit less than one week away, Monday's small protest and arrests represent just a small sliver of what is expected in the days to come. There are growing indications that the gathering of world leaders is near. NATO flags started to appear over the weekend, and parking bans near McCormick Place have gone into effect. Cars left parked on Indiana between Cermak and 24th Street were towed. Indiana is the first north-south street west of McCormick Place. More parking restrictions and road closures will be added later in the week. Click here for more information on closures and restrictions.
Overnight, Chicago police became more visible in the Loop and on the Magnificent Mile. Squad cars, police vans and some SUVs were parked on Michigan Avenue -- some on the side of the street, others in the median. Numerous officers were also seen walking the sidewalk.
Meanwhile, Monday's protesters remained nonviolent, and the arrests happened peacefully. The group even said the police handled the situation very well.
"Who knows? We don't know what the police response is going to be this week, but we're happy that things were even handed on the police side," Olzen said.
Among those arrested were two from Chicago, three from Iowa, one from Los Angeles, one from Indiana and one from Champaign. They were charged with criminal trespassing.
Ambassador Dana Hunatova of the Czech Republic says without the support of NATO her country may never have broken free of the Soviet Union.
"Thanks to NATO there is no war in Europe since the end of the second World War, so we see NATO completely differently," said Hunatova. ""NATO for us is a symbol of our freedom."
Also on Monday, Occupy Chicago joined the Chicago Teachers Union to protest the closing of an art program at Dyett High School on the South Side.
So far Mayor Rahm Emanuel says his police department has it under control.
"We'll protect public safety and also public speech. Both will be achieved," he said.
The NATO summit is next Sunday and Monday.
(The Associated Press contributed to this report.)