[1] Byrne grew up in Salt Lake City and attended both the University of Utah and Mount Vernon College in Ohio.

Byrne served in the Virginia House of Delegates for six years, having defeated two-term Republican incumbent Gwen Cody in 1985.

[citation needed] Thomas M. Davis, then chairman of the Fairfax County Board of Supervisors, defeated her for re-election in 1994's "Republican Revolution."

His campaign charged that Byrne was too liberal for the swing district she represented and that her voting record was too supportive of President Bill Clinton.

In 1998, Byrne began work at the United States Information Agency, advising its director on the au pair program.

In the Virginia Senate, she sponsored legislation to prohibit people from sleeping in rooms except bedrooms, a response to complaints of students and poor immigrants crowded into residential houses.

In the primary election on June 10, 2008, she faced Gerald Connolly, chairman of the Fairfax County Board of Supervisors, and others in a multicandidate field.