LEFT: A photo of Reitman as a senior at Harvard-Westlake High School. RIGHT: Jason Reitman with Up in the Air star George Clooney at the film’s LA premiere

TRYING TO BOIL down my experience of growing up in Los Angeles is almost impossible. The defining moments of my childhood are as diverse as LA itself. Instead, I offer you a series of fragments from a very happy string of years spent in every area code this city has to offer. Perhaps when viewed all together, these memories will give you a sense of why I love LA—and why I’ll probably never leave.

★ Taking my first girlfriend up to Mulholland just weeks after getting my license and parking with a view of the Valley. We were half-naked in the backseat when a park ranger flooded my rear window with his high beams. After a lecture, he gave me a ticket for illegal parking.

★ My elementary school held a full-scale, daylong earthquake drill in which we actually ate rations and never left the football field. Two students got picked from each class to have injuries. I got broken fingers.

★ Forgetting my lines in the Grandparents' Day play and making up an entirely new scene as my costar, Jen Benjamin, looked at me like I was crazy.

★ The one day in fifth grade when, in a sudden display of mob mentality, my entire class ran outside to experience the miracle of snowfall in Los Angeles.

★ Picking up KFC with my dad on the way to the Great Western Forum to watch Magic [Johnson], Kareem [Abdul-Jabbar] and [James] Worthy wipe the floor with the rest of the NBA. I honestly don’t remember seeing them lose.

★ Ditching ninth period to go to Henry’s Tacos.

★ The day my school bus broke down in Coldwater Canyon. My best friend, Andrew, was the son of a music manager. He convinced the bus driver we’d be fine, and we proceeded down the hill to Eddie Van Halen’s house. We spent the afternoon playing stand-up video games in Van Halen’s home studio as the band recorded For Unlawful Carnal Knowledge.

★ Getting dropped off at the Cineplex Odeon Universal City Cinemas around noon with a $20 bill and getting picked up at nightfall.

★ Attending the Eyes Wide Shut premiere at the Mann Village Theatre—an impossible ticket. Knowing I was a Kubrick fanatic, my mom bowed out and let me attend with my father. I remember Kubrick’s three daughters standing up in the audience before the screening to a round of applause. The afterparty was one of the last events to take place at Chasen’s. By the time I entered that building again, it was a grocery store.

★ Sneaking under the fence at Hawthorne Elementary School to play roller hockey.

★ Watching a Doberman chase a mailman down Maple Drive. I stopped to call the police when a platinum-blonde, middle-aged woman in a Rolls-Royce drove by slowly, craning her head out the window as she screamed the dog’s name, “Diamonds!”