Boehm's green Schwinn bicycle is also missing, according to authorities.
Despite filing a missing person report with a national police database and the Evanston Police Department, officials say they have not turned up any leads.
Calls made to Al Cubbage, the vice president for university relations, were not immediately returned. A source at the Evanston, Ill., school said Boehm's parents came to visit for parent's weekend to discover he was missing.
A woman who answered the phone at the Boehm family's home in Monument, Colo., declined to comment about the student's disappearance.
But Boehm's grandmother, Laverna Boehm, told ABCNews.com in a telephone interview that "everyone is praying" for the safe return of her grandson.
She said that Boehm had been busy with school and was a talented actor. According to the university, Boehm was enrolled in the School of Communication.
Sasha Puchalla, a Northwestern junior who has known Boehm since they attended same private high school in Colorado, told the campus newspaper that her friend "really enjoyed being around people and has a lot of fun with life in general."
"He is just such a vibrant person," Puchalla told the Daily Northwestern. "He is very caring and compassionate."
Another one of Boehm's high school friends, Tyler Boschert, told ABCNews.com that it's not like Boehm to simply disappear.
"From everything I've heard it seemed like he was doing fine," said Boschert. "He had friends and was enjoying things."
Boschert, 18, is a sophomore at the university but said that because he lives on the opposite side of campus from Boehm the two didn't see each other very often. He added that Boehm did not have a roommate.
Boschert said that Boehm's Facebook page which is closed to the public has messages from friends asking why he hasn't returned phone calls or e-mails.
According to Boschert, Boehm had left Northwestern in the middle of last semester but he did not know why.
As for his family, Boschert said that they seemed "tight-knit" and "not at all dysfunctional."
"I'm pretty confident that he'll deal with anything thrown his way and he'll turn up," said Boschert.
Boehm is described as a white male, 5 feet 10 inches tall, weighing approximately 145 pounds, with brown hair and brown eyes. He has a small birthmark on his right forearm.
Anyone with information about Boehm's whereabouts can call the Northwestern University Police at 847-491-3254.
