conservative political party formed from various local and sectional organizations that took power in 1912, following a general election in 1911, and held control of the government until 1928. The Reform Party first acted as a united group in 1905, but it was not formally constituted and organized along party lines until after the 1911 election.

Based primarily on urban business interests and the small farmers of the North Island dairy industry, the Reform Party won the 1911 election by a promise to transform agricultural leasehold property into freehold on terms that would enable farmers to reap a significant profit from the sale of their land. It also benefited from its opposition to growing labour union defiance of New Zealand's antistrike Industrial Conciliation and Arbitration Act (1894).

Led by W.F. Massey (Massey, William Ferguson), the party's leader and New Zealand's premier from 1912 until his death in 1925, the Reform Party dealt violently with the strikes of 1912–13. But it was mortally weakened during the depression of the late 1920s, when its business and agrarian wings turned against one another. The Reform Party returned to power in coalition with the United Party (1931–35) but was formally dissolved in 1936. Its remnant entered the new National Party.