On graduation day at Buffalo Glenn High School in Tacoma, Washington, valedictorian Denis Cooverman (Paul Rust) confesses his love for head cheerleader and long time crush, Beth Cooper (Hayden Panettiere) in his speech while also taunting Valli Wooley (Marie Avgeropoulos), a girl with an eating disorder, and an ignorant bully, Beth's Army soldier boyfriend Kevin (Shawn Roberts); and urging his best friend Rich Munsch (Jack T. Carpenter) to 'come out of the closet' and finally admit he's gay. Afterwards, Denis invites Beth and her friends, Cammy (Lauren London) and Treece (Lauren Storm), to a party he has planned at his house.
At Denis's house, his parents leave but not before his father (Alan Ruck) revealing that he has condoms upstairs if he needs them. Beth, Cammy, and Treece arrive at Denis’s house for the party. Kevin and his trendy four-wheeler soon come barging in, with his Army buddies vowing revenge on Denis. They attempt to beat Denis up, but it results in Denis, Beth, Rich, Cammy, and Treece escaping in Beth's car.
They drive to a gas station hoping to get beer, but are told by the convenience store clerk (Samm Levine) that he will not accept the driver’s license Beth gave him which states that she is 37. So Beth bribes the clerk with a kiss. He accepts, which makes Denis realize that she is not who he thinks she is. They then start a bonfire in an isolated section of town where Rich, Cammy, and Treece are chased by a stampede of cows after trying to tip one over. Denis then puts on the song "Beth" by KISS and is told that she was named after that very song. Denis thinks it's cool that Beth has two "headbangers" for parents. In Beth's eyes one can see she's slowly warming to Denis, and is becoming aware that he truly does genuinely love her, much to her amazement.
They all get in crazy reckless driver Beth’s Echo and drive without lights. They then stumble upon Denis's father and mother (Cynthia Stevenson) (who are both having car sex) by almost crashing into them. Rather than facing Denis’s father with his pants down, Beth decides to drive them away unseen to a private party at Valli Wooley’s house, encountering Kevin once again who had tracked them there. Kevin challenges Denis to a fight, as a now fed-up Beth crashes his car through the wall of the house. They drive away in Kevin’s Hummer H2 to the vacant Buffalo Glenn High School, parking halfway up the front flight of stairs, and enter the school with Beth’s head cheerleader key. After showcasing their cheerleading routine, Beth, Treece, and Cammy decide to run to the girls' locker room to take a shower. Just as Denis is undressing to join his friend and the girls in the shower, Kevin and his buddies appear in the locker room and jump him once again. Rich challenges Kevin and his friends in a towel whipping 'duel', as he has been training for years after being towel whipped as a bullied young kid. Rich finally manages to defeat the three guys, towel-whipping them unconscious down a flight of stairs. They escape to Treece's father's cabin in Beth's Echo where Rich, Treece, and Cammy have a threesome, as Beth and Denis enjoy the sun rise and finally share their first kiss.
They head to Denis's house afterwards where his parents are delighted to see he has 'hooked up' , but make him aware he still needs to be punished for leaving the house in a wreck. Beth says goodbye to Denis, gives him a kiss, and touchingly thanks him for loving her. Denis tells her "what's not to love" and that she mustn't forget that. Then promises that he will see her at their high school reunion and if they are both still single that he will marry her. Beth smiles and tells him it's a deal. After Beth leaves with Treece and Cammy, Rich proclaims to Denis that he might be gay after all, or perhaps bisexual (plus jokes that after last night's antics he's still more heterosexual than Denis). Denis informs Rich that he was just playing about waiting until the reunion to talk to Beth again. He tells Rich that he is going to leave Beth a message on Facebook and ask her out. Rich disagrees with him and tells Denis that he should make a grand gesture by going to her house with a boom box and wait for her. They then begin debating on how Denis should go about asking Beth on a date.
In early 2008, producers announced the novel I Love You, Beth Cooper would be made into a film, with actress Hayden Panettiere in the title role. Filming began in 2008, with a release slated for July 10, 2009. The film was directed by Chris Columbus, with the screenplay written by Doyle.
Filming took place at Centennial Secondary School, Magee Secondary School and at St. Patrick's Regional Secondary; which are all located in Vancouver, British Columbia.
The film's official website was launched on February 14, 2009 with a Valentine's Day themed "personalize your own trailer and e-card" widget that allowed for customization of the trailer and that could be sent to loved ones, friends and family.
The film was produced and originally to be released by Fox specialty subsidiary Fox Atomic, but theatrical distribution reverted to 20th Century Fox after Atomic folded in April 2009.
The first track is performed by Christopher Columbus' daughter.
In its opening weekend (July 10–12), the film grossed $4,919,433 at 1,858 theaters, which was enough for seventh place, and it finished its worldwide theatrical run with $15,821,907.
The film was subject to many negative reviews. Rotten Tomatoes gave a rating of 14% based on 110 professional reviews. The consensus states: "Heavily reliant on stereotypes and shallow teen comedy clichés, I Love You Beth Cooper is a humorless affair that fails to capture the charm of its source novel." Ben Lyons from At the Movies called the film "The Worst Film of 2009 So Far", criticizing it for its stereotypical portrayal of high school students and glorification of drinking and driving.
Cinematical stated that much of the dialogue was lifted directly from the book, but when spoken on screen, the lines fall flat. "The adaptation from R-rated novel to PG-13 film comes into play." In a scene where Beth and Denis try to buy beer, Beth offers to kiss the store clerk so that she can buy the beer but the viewer does not see the kiss. Cinematical calls Panettiere's performance unconvincing as a "rule-breaking girl who walks on the wild side".
Rolling Stone was highly critical of director Chris Columbus. The publication felt that Columbus flattened every joke and sucked the life out of the actors. In addition, the publication felt that Columbus' flair for sight gags reached its peak when Denis uses two tampons to stem a nosebleed.