Helen Clark elected Prime Minister

Helen Clark came from a National-leaning rural family but developed her politics while studying and lecturing in political science at the University of Auckland. She won the Mount Albert seat for Labour in 1981, served as a minister in Labour's second term from 1987, holding portfolios including housing, health and conservation, and was Deputy Prime Minister from 1989 to 1990 under Geoffrey Palmer and Mike Moore. After Labour's narrow defeat in the 1993 election she challenged Moore for the leadership and won, becoming Leader of the Opposition on 1 December 1993. In 1996 she polled so badly that a coup against her was attempted, but she stayed on.

Labour had been in opposition since 1990. Clark repeatedly said she wanted Labour to 'govern alone', but before the 1999 election the party made overtures to the left-wing Alliance. The two had not got on, largely because one of the Alliance's key members was NewLabour, set up by Jim Anderton, a former Labour MP who had quit the party in protest at Roger Douglas's economic reforms. Clark addressed the Alliance's annual conference in August 1998, and shortly before the election the parties reached a formal understanding on a possible coalition. They faced a National government that had lost its coalition partner in 1998 and kept office through agreements with defecting MPs. The election, held on 27 November 1999, was the first in New Zealand in which the leaders of both major parties, Clark and Prime Minister Jenny Shipley, were women.

Labour won 49 seats, 12 more than in 1996, and National 39. With the Alliance's 10 seats, a coalition of the two was still two seats short of an absolute majority, so it governed with support from the Green Party, which entered Parliament as an independent party for the first time. Its entry was narrow. Only when special votes were counted did co-leader Jeanette Fitzsimons win Coromandel, by 250 votes, and the party's share of the vote reach 5.16%. New Zealand First fell from 17 seats to five, and would have left Parliament had Winston Peters not held Tauranga, by 63 votes. Labour also won back the Māori seats it had lost in 1996. The new government, with Anderton as Deputy Prime Minister, was sworn in on 10 December. Clark became the first woman to become Prime Minister following an election.

The new government reversed parts of the 1990s reforms. It reintroduced income-related rents for state houses, set at 25% of a tenant's income, and stopped state-house sales. It repealed the Employment Contracts Act and replaced it with an Employment Relations Act more friendly to unions and collective bargaining. At the Alliance's behest it created a state-owned bank, Kiwibank. It bought a majority stake in the national airline, Air New Zealand, re-established partly elected district health boards, and introduced paid parental leave, at first for 12 weeks. It also dropped titular honours and established a Supreme Court, ending appeals to the Privy Council. In Gavin McLean's reading for NZHistory, Clark 're-centred policy', softening but not overturning the fundamentals of 'Rogernomics'.

The Alliance broke apart before the end of its three-year term as Labour's coalition partner. Labour, in NZHistory's words, 'crushed' National at the 2002 election, and in 2005 National ran it close, but Labour won again, making Clark the first Labour leader to win three consecutive elections. During her time in office women held several of the country's leading posts, and from March 2005 to August 2006 the offices of Governor-General, Speaker of the House and Chief Justice were all held by women at once. Labour lost the 2008 election, and Clark announced her resignation as leader on election night. By then she was New Zealand's fifth-longest-serving Prime Minister. Throughout her premiership she was also Minister for Arts, Culture and Heritage; NZHistory credits her with increasing arts funding and raising the profile of the country's military heritage. Early in 2009 she left for New York to head the United Nations Development Programme, a role she held until 2017. In 2016 she stood unsuccessfully to become secretary-general of the United Nations.