Glynn's first movie appearance was as Mae Barber in Three Days of the Condor (1975). She is also known for her role as mother to Molly Ringwald's character in Sixteen Candles (1984), and as daughter-in-law to Geraldine Page's character in The Trip to Bountiful (1985). Her other film credits include roles in Resurrection (1980), Continental Divide (1981), The Escape Artist (1982), Gardens of Stone (1987), Blood Red (1989), Night Game (1989), Convicts (1991), Judy Berlin (1999) and Whiskey School (2005).
A life member of The Actors Studio, Glynn made her belated but Tony-winning Broadway debut - as 1979's Outstanding Featured Actress in a Musical - portraying "Mona Stangley" in the original production of The Best Little Whorehouse in Texas, a musical comedy adapted by Glynn's husband and fellow Studio member, Peter Masterson, from a non-fiction article published in Playboy Magazine, in collaboration with the article's author, Larry L. King, and Songwriter Carol Hall, and developed at length in workshop performances at the Studio. Glynn's award-winning performance would be reprised in the 1982 revival.
