The Socialist Labor Party (SLP) is a political party in the United States. It was established in 1876, and was the first socialist party formed in the country.
Descended from the Workingmen's Party of the United States, the party changed its name in 1877 to Socialistic Labor Party and again sometime in the late 1880s to Socialist Labor Party. The party was additionally known in some states as the Industrial Party or Industrial Government Party. In 1890, the SLP came under the influence of Daniel De Leon, who used his role as editor of The Weekly People, the SLP's English-language official organ, to expand the party's popularity beyond its then largely German-speaking membership. Despite his accomplishments, De Leon was a polarizing figure among the SLP's membership.