The New Zealand Socialist Party was founded in 1901, promoting the works of Karl Marx and Friedrich Engels. The group, despite being relatively moderate when compared with many other socialists, met with little tangible success, but it nevertheless had considerable impact on the development of New Zealand socialism. It was one of the parties that united in 1916 to form the New Zealand Labour Party.
The party was founded by members of the 'Clarionettes', a group of about 190 English Socialist immigrants recruited through William Ranstead's weekly publication. The original goal was to establish a socialist colony, though the colony was never organized. The Wellington branch of the party was founded on 28 July 1901, and the Christchurch branch in January 1902. Some of the most prominent leaders of the party were Frederick Cooke, Ted Howard, and Tom Mann. By 1903, Robert Hogg was publishing a party journal called the "Commonweal" in Wellington. Membership had increased to 3,000 by April 1908.
A different group, the Socialist Party of New Zealand, was founded in 1930 and became the World Socialist Party (New Zealand).