Clark joined the Labor Party in 1971. She has held office at every level of the New Zealand Labor Party (NZLP). In 1973–75 she was President of the Labor Youth Council and a member of the Auckland Labor Regional Council. In 1975 she ran unsuccessfully for a seat as a Member of Parliament (MP) in Piako. Clark was Secretary of the Labor Women's Council in 1977. She was a Labor Party Executive in 1978–88. Clark represented the Labor Party at congresses of the Socialist International and the Socialist International Women in 1976, 1978, 1983, and 1986 at an Asia-Pacific Socialist Organization Conference held in Sydney, Australia, in 1981, and at the Socialist International Party Leaders Meeting in Sydney in 1991. Clark was also a government delegate to the World Conference to mark the end of the United Nations Decade for Women in Nairobi, Kenya in 1985. In 1981 Clark was elected as the Labor candidate for Member of Parliament (MP) for Mt. Albert. Clark stood successfully as the Labor candidate for Member of Parliament (MP) for Owairaka in 1996–99. On 27 November 1999, the New Zealand Labor Party won the majority and Helen Clark was elected as prime minister of New Zealand.