The Workers Party was a Trotskyist group in the United States. It was founded in 1940 by many leading members of the Socialist Workers Party who opposed the Soviet invasion of Finland. They included Martin Abern, Hal Draper and Max Shachtman, who became the new group's leader. As a result, the party's politics are often referred to as Shachtmanite.

Having taken nearly half the membership of the SWP and a majority of the Young Peoples Socialist League, the Yipsels, the WP was initially estimated as having approximately 500 members. Although it recruited among workers and youth during the war years it never grew substantially despite having more impact than its numbers would suggest.

The group soon developed a bureaucratic collectivist analysis of the Soviet Union, and a third camp perspective, being the first to use the slogan "Neither Washington nor Moscow". It also contained a minority tendency which was grouped around the figures of two leading intellectuals CLR James and Raya Dunayevskaja. This tendency took the name the Johnson-Forrest Tendency for its principle leaders cadre names. It developed the viewpoint that Russia was state capitalist and left the WP in 1947 in order to rejoin the SWP.

Working in the labor movement, the party grew rapidly, with members such as Irving Howe and Michael Harrington joining.

In 1949, the group renamed itself the Independent Socialist League. It was removed from the US Attorney General's list of subversive organizations after a lengthy court battle, but failed to grow as the right wing around Howe and Harrington split to work with the Dissent journal.

In 1957, the ISL joined the Socialist Party of America. Some members took leading positions in the Socialist Party, but moved increasingly to the right. A small group around Hal Draper left to form the Independent Socialist Clubs.