Streep and Lohan play mother and daughter in the film, inspired by Garrison Keillor's beloved radio show and in theaters Friday.
Although Lohan has enjoyed success in several youth-oriented movies, her talent is often eclipsed by reports of her alleged hard-partying ways.
Asked in New York what she thought about Lohan, the "Adaptation" and "The Hours" actress told reporters she liked her flame-haired co-star and was impressed by her acting ability.
"I knew she was a really, really good actress because I have committed 'Freaky Friday' to heart. It's like a religious experience in my house. I have three girls and they love that movie," Streep said.
"She's really good in all those movies, even when she was a little bitty thing in 'The Parent Trap' and there is a reason they put these big, important movies with a lot of money riding on them on her little shoulders, because they know she's going to do it," she continued. "I knew she was a good actress, but I didn't know she'd be just so cool and sweet. She's a good girl."