Frelich was born in Devils Lake, North Dakota to deaf parents Esther (née Dockter) and Phillip Frelich, and was the eldest of nine siblings (all deaf). She attended North Dakota School for the Deaf, graduating in 1962, and then went on to study at Gallaudet College (now known as Gallaudet University), a school for the deaf and hard-of-hearing.

Frelich attended the North Dakota School for the Deaf and Gallaudet College. At the latter she completed a degree in library science, but also participated in theater. It was at Gallaudet that she was seen performing by David Hays, one of the founders of the National Theater of the Deaf, who asked her to join the theater company.  Frelich originated the leading female role in the Broadway production of Children of a Lesser God, written by Mark Medoff. Children won the Tony for Best Play; Frelich won the 1980 Best Actress Tony Award and her co-star, John Rubinstein, won Best Actor Tony Award. Marlee Matlin played Frelich’s role in the film version, for which she won the Academy Award for Best Actress. Frelich later starred in other plays written by Medoff, including The Hands of Its Enemy and Prymate. She was nominated for an Emmy Award for her performance in the 1985 television movie Love Is Never Silent. Frelich appeared in the recurring role of Sister Sarah on Santa Barbara. Her last acting role was in an episode of CSI: Crime Scene Investigation in 2011.

Frelich was married to Robert Steinberg for many years, and they had two children (both of whom can hear and are fluent in American Sign Language). She performed the ASL interpretation of Jewel’s rendition of the national anthem at Super Bowl XXXII.  Frelich died on April 10, 2014 at her home in Temple City, California at the age of 70 on April 2014 from progressive supranuclear palsy, a rare degenerative neurological disease for which there are no treatments.  News of her death broke on the Deaf West Theater Facebook page. The post honored Frelich for “paving so many roads for the Deaf Community.A leading light of our community has been lost, and we mourn deeply. Our thoughts are with her family.”