The origins of the SEP lie in the Socialist Workers Party (SWP) of the early 1960s. Tim Wohlforth was a youth leader in that party and was opposed to the course of the organisation. With others, including James Robertson, he formed a tendency within the SWP called the Revolutionary Tendency (RT). It developed links with Gerry Healy's Socialist Labour League in Britain.
The two main leaders of the RT had different evaluations of the SWP. Robertson's position led the SWP to expel him and his supporters first. Wohlforth's split the RT by remaining in the SWP. His supporters formed a group named the Reorganised Minority Tendency, but were themselves expelled a short while later. They then formed the American Committee of the Fourth International (ACFI) and became the United States section of the ICFI now dominated by Healy.
The ACFI grew throughout the 1960s along with every other leftist grouping. Many of its recruitment techniques were directly cribbed from those used by the Healyite WRP in Britain. Thus youth recruitment was based on drawing youth towards the group based on the organisation of events which combined entertainment and politics. Recruits were then encouraged to work for the group carrying out tasks at a frantic rate. The result was a high level of recruitment but the swift loss of most recruits through 'burnout'.
The ACFI was renamed the Workers League (WL) and did develop into a nationwide organisation of some hundreds of members. But if burnout was a problem for rank and file members it was a major problem for the leadership around Tim Wohlforth and Nancy Fields and a collapse developed in 1972. Having aped the British Healyites and basically subjected themselves to them when Healy decided that Wohlforth and Fields were no longer the right people to run the WL they had no defence. Therefore when Healy declared that Wohlforth and Fields were agents of the CIA all they could do was resign from the WL in abject defeat.
In the midst of turmoil in Healy's group, by then called the Workers Revolutionary Party, the group renamed itself the Socialist Equality Party in 1984. It is now based in Michigan and occasionally endorses presidential candidates; it most recently endorsed John Christopher Burton when he ran in the California recall. The party publishes a website called the World Socialist Web Site and an occasional journal, the World Socialist Web Site Review.