Despite the controversial Iranian leader's history of making inflammatory statements and his suspected terrorist ties, many students said he had a right to speak at the Ivy League school. And some support for the president was evident in signs and banners posted around the campus alongside those condemning his visit.
"I'm not protesting his right to speak," said sophomore Sarah Brafman, 19. "I'm protesting him and his administration's policies."
Brafman said she was not speaking on behalf of any organization, but she, like many students protesting Ahmadinejad's visit, wore black T-shirts distributed by a group calling itself the Columbia Coalition.
For each sign placed on the wall of a building or on a sidewalk protesting the speech, another supporting the Iranian president, or attempting to paint his regime in a positive light, cropped up next to it.
Posters that purportedly showed two gay men that had been beaten at the hands of the Iranian police hung next to signs that read "Iran had the second most Jewish citizens in the Middle East next to Israel" and that its parliament had Jewish and Zoroastrian lawmakers.
Many of the students protesting Ahmadinejad's visit insisted that despite earlier media reports, the tenor of the protest was less about banning the president from campus and more about protesting his policies.
Those policies include being "anti-free speech, anti-women's rights, anti-gay rights and calling for the annihilation of a U.N. member state," said Lauren Steinberg, 20, a junior and a political science major.
"Now that he's here, it is important we challenge him," she said.
A number of those who make up Columbia's Iranian student body, many of them women in head scarves, were also present at the center of campus.
Zeinab Fard, a 25-year-old graduate student studying economics, estimated there were more than 100 Iranian students at Columbia.
"It's good that Ahmadinejad is speaking here directly and not through the filter of the American media, which sometimes twists his words," she said.
"Iranians have never bothered the United States, and America has many times attacked Iran. It is important that Americans hear what he has to say. He has a right to be here," Fard said.
One member of the Iranian community said Ahmadinejad did not represent the values of a large part of the country, but his presence on an American university campus was an important symbol to the American people.
"Many Iranians know he is a bit crazy," said Atefeh, the 26-year-old Iranian wife of an engineering student who asked that only her first name be used.
"He was supported mostly by the poor and uneducated. It is good that he is here because this is an occasion in which many Americans will get to learn about the beautiful country of Iran for the first time."
Despite reports that the Iranian government has supplied Iraqi insurgents with materials to kill Americans, one student, a military veteran who served in Germany outfitting U.S. jets with bombs, said Ahmadinejad had a right to speak.
"It is really important that he's here and a dialogue has opened up," said Aaron Bliese, 27, a creative writing graduate student.
"Didn't we learn anything from the last four years? Maybe if we had sat down with Saddam in the first place, and listened to what he had to say, the war could have been diverted. It's important to have a forum."