Dan Jinks ("American Beauty," "Milk") has signed on to produce.
"Leah Rachel, at only 25 years old, is the freshest and funniest writer I've come across in some time," Jinks said in a statement. "Her script has the potential to become a touchstone movie for a generation, like 'American Graffiti' or 'Sixteen Candles' were years ago."
The movie is about "the delusion, desperation and absolute euphoria of first loves," reads Mandate's sparse logline for the project.
HBO has already picked up Rachel's pilot "Starf*cker," with Stephen Levinson and Mark Wahlberg producing.
The show is about a group of female friends in Los Angeles. She also has a single-camera half-hour sitcom set up at ABC, with Jamie Tarses and Julia Franz producing. That show came from a blind deal Rachel had with Sony Pictures Television.
She also is writing an adaptation of the book "Here Lies Bridget," with Kat Coiro ("Life Happens") directing.