D'Alesandro, whose father was a politician and New Deal Democrat, studied political science at Trinity College in Washington, D.C., graduating with a bachelor's degree in 1962. The following year she married Paul Pelosi, and the couple moved to New York. Five children and six years later, the family settled in San Francisco, where Pelosi worked as a volunteer Democratic organizer. Earning a reputation as a highly effective fund-raiser, she rose through the ranks, serving on the Democratic National Committee and as chair of both the California Democratic Party (1981–83) and the host committee for the 1984 Democratic National Convention in San Francisco. Along the way, Pelosi befriended longtime U.S. Rep. Phil Burton. Burton died in 1983 and was succeeded by his wife, Sala, who, shortly before her death in 1987, urged Pelosi to run for the seat. She narrowly won a special election and was reelected in 1988 to a full term. Pelosi easily won subsequent elections in her overwhelmingly Democratic district.

In 2002 Pelosi was elected minority whip and—using what she referred to as her “mother of five” voice—began pushing for unity among the diverse factions within her party by embracing conservatives and moderates. Still, Pelosi continued to vote consistently in favour of such liberal causes as gun control and abortion rights, opposed welfare reform, and cast a vote against the Iraq War. Her criticism of Pres. George W. Bush (Bush, George W.) could be harsh; she once characterized him as an “incompetent leader.” Her critics in turn claimed that her “left coast,” left-wing politics put her out of touch with most of the country.

Following the midterm elections in November 2006, the Democrats gained a majority in the House of Representatives. On Jan. 4, 2007, Pelosi was elected speaker of the House of the 110th Congress.