Don't let the title of this movie mislead you. 100 Girls is really about one guy, a college freshman named Matthew (Jonathan Tucker) who finds himself stuck in an elevator with a young woman during a blackout. They make love, but she is gone when he wakes up in the morning. He never saw her face but believes himself in love with her.

The rest of the film is about Matt's quest to find "the one." All he has is her panties, so he goes about trying to find the matching bra by sneaking into all the rooms in the dorm. When that doesn't work, he makes friends with the girls who live there, trying to ferret out his love. He even resorts to posing as a woman himself.

Much of Matt's dialog and voiceover is about the differences between men and women, men's fears, and the struggle to figure out how to be a man. Unfortunately, it also contains anti-feminist rants, especially directed towards the Women's Studies class professor. What might be a cute comedy in some ways becomes annoying with these elements, in addition to some adolescent sexual anatomy jokes.

In the last ten minutes, two of the students are revealed to be lesbians. One is not a surprise. Arlene (Katherine Heigl) earlier defeated Matt in a game of strip fusball. Wendy (Larisa Oleynik), on the other hand, is the former high school classmate whom Matt thinks is the kind of girl who would make a perfect wife. Turns out she helped Matt with his search, hoping that he would find a girl for her too. Matt does find love in the end, as do Arlene and Wendy.