Robbins, who played jailed banker Andy Dufresne in the 1994 classic, is holding weekly five-hour classes for inmates at the medium-security California Rehabilitation Center in Norco, California.
The classes are run by The Actors' Gang, a theatre company set up by a group of screen stars including Robbins in 1981.
He tells CBS Los Angeles, "They're asked to do things they've never been asked to do in their life - open up emotionally, and put make-up on and costumes on, and pretend to be people. It's weird stuff.
"You never are encouraged to express your emotions in prison, and this class says it's okay to feel this kind of emotion, to respond with fear to a threat, to have empathy for someone that is constantly hostile. It's okay to laugh at the absurdity of a situation."