[1][2][3] A native of Southern California, Plumb began appearing in commercials at age seven, and also had guest roles on the televisions series Family Affair, The Big Valley and The Virginian between 1966 and 1967.

She made her feature film debut with a minor role in I'm Gonna Git You Sucka (1988), and later appeared in Gregg Araki's black comedy Nowhere (1997).

(She was also cast as "Bonnie Braids" in a TV pilot version of the comic strip Dick Tracy, but does not actually appear in the program itself, only in the opening credits.)

In 1968, she appeared on It Takes a Thief and Family Affair; in the latter, she played a terminally ill girl on the episode "Christmas Came A Little Early".

Her featured storylines included Jan's embarrassment over not having a boyfriend, concerns about her future appearance, being a middle child, and her insecurity over wearing glasses.

The sitcom has never left the television airwaves and eventually spawned numerous spin-offs, reunion specials, feature films, and parodies.

Several episodes of the sitcom featured the Brady kids singing and as a result, Plumb and the rest of the younger cast recorded several albums.

[5] Plumb was the only original cast member who declined to reunite for the 1976–77 variety show The Brady Bunch Hour on ABC.

[citation needed] Her role would be filled by Geri Reischl, who went on to be known among Brady Bunch fans as "fake Jan".

To promote their latest incarnation, the cast appeared on an episode of Sally Jessy Raphael, which is remembered for having been shot outdoors in Florida during a rainstorm.

In 1995, Plumb was a member of the cast of the Saturday morning sitcom Fudge, playing the title character's mother, Mrs. Anne Hatcher.

In 2007, Plumb was the only surviving cast member who was not on hand when TV Land honored The Brady Bunch with its Pop Culture Award.

Plumb appeared in several made-for-television movies, including The House on Greenapple Road (1970), The Force of Evil (1977), Telethon (1977), Secrets of Three Hungry Wives (1978), The Night the Bridge Fell Down (1983) and Yesterday Today (1992).

Her film credits include I'm Gonna Git You Sucka (1988), ... And God Spoke (1993), Nowhere (1997), Breast Men (1997) and Manfast (2003).

[7] In 2010, Plumb originated the title character in the New York production of Miss Abigail's Guide to Dating, Mating and Marriage, inspired by a book and website of the same name.