Lange became active in politics when he joined the Labour Party in 1963, while he was still at university. He first tried to get elected to the Auckland City Council in 1974, but did not get enough votes. In 1975, he tried to get a seat in Parliament, but again was unsuccessful. A third attempt in 1977 was successful and he won the seat of Mangere. He held this seat until he left politics in 1996. His first speech in the parliament was very successful and he was seen as a possible leader of the Labor Party. In 1979 he was made the Deputy Leader, and in 1982 Lange was made the leader. When the Labor Party won the elections in 1984, David Lange became Prime Minister of New Zealand.