Socialist Organizer is a Trotskyist political organization in the United States. It originated in a 1991 split from Socialist Action (SA) led by Alan Benjamin—then editor of the Socialist Action newspaper—who had developed sympathies with the "Fourth International (ICR)" current of Trotskyism. Failing to win SA as a whole to their politics, about a dozen activists were expelled from Socialist Action after attending the founding conference of the International Liaison Committee for a Workers' International (ILC) in Barcelona, Spain, which SA had prohibited them from attending. These activists then went on to form Socialist Organizer.