The LOL star will play a mother to Elizabeth Olsen's character, who is best friends with Dakota Fanning's character, reports Deadline.
The story revolves around two young best friends who want to lose their virginity, but find their friendship tested when they fall in love with the same boy.
The Naomi Foner-directed movie, which will begin shooting in New York in June, also features Peter Sarsgaard.
Earlier this year, Moore checked into rehab after she collapsed from apparently smoking an unspecified substance in her Los Angeles home on January 23.
She is said to be said to be doing well since leaving the facility.
Watch the trailer for LOL below: