Socialist Organiser was the name of a defunct weekly socialist newspaper circulated in the British Labour Party . The newspaper was founded by the 1979 Socialist Campaign for a Labour Victory, initiated by the group now known as the Alliance for Workers' Liberty.

Initially, contributors to the paper included Ken Livingstone, Jeremy Corbyn and Peter Tatchell, but a split over the tactic of raising taxes to pay for improved services led to many of these big names leaving.

In the mid-1980s, the paper was sued by the Workers Revolutionary Party over claims they repeated that the WRP was partially funded by money from the Libyan and Iraqi governments, but the WRP was forced to abandon the action.

Socialist Organiser was banned by the Labour Party in 1990, but it continued to be published until the mid-1990s, when the AWL launched their new newspaper, Action for Solidarity. This fortnightly paper is now known simply as Solidarity.