Armstrong also starred in the ABC drama series My So-Called Life and had lead roles in a number of made-for-television films.

[2][3] She attended the Bryn Mawr School for Girls and Brown University, from which she graduated with degrees in Latin and Theater (studying acting with Jim Barnhill and John Emigh).

with Desi Arnaz Jr. She co-starred again with Richard Thomas in a 1981 stage production in Seattle of Neil Simon's Barefoot in the Park, from which a video was made for HBO broadcast that year.

Armstrong continued to make several films for both the big and small screens in the 1980s, among them High Road to China opposite Tom Selleck; Jaws 3-D with Dennis Quaid; Alan Alda's The Four Seasons; the TV miniseries Lace; and Nothing in Common, starring Tom Hanks and Jackie Gleason.

The 1990s brought Armstrong to her best-known role, playing Patty Chase on the series My So-Called Life.