The Socialist Campaign Group (Welsh: Grŵp Ymgyrch Sosialaidd), also simply known as the Campaign Group, is a UK parliamentary caucus of the Labour Party including Members of Parliament in the House of Commons. The group also includes some MPs who formerly represented Labour in Parliament but have had the whip withdrawn or been expelled from the party.

The group was formed in 1982 following the 1981 Labour Party deputy leadership election when a number of soft left MPs, led by Neil Kinnock, refused to back Tony Benn's campaign, leading a number of left-wing Benn-supporting MPs to split from the Tribune Group to form the Campaign Group. It was at a meeting of the Campaign Group in 2015 that the decision was taken that Jeremy Corbyn would contest for the leadership of the Labour Party. The Campaign Group maintains close links with Momentum.

The Socialist Campaign Group was founded in 1982 owing to a disagreement within the Labour left, traditionally organised around the Tribune Group, about whom to back in the 1981 Labour Party deputy leadership election. Tony Benn's decision to challenge Denis Healey for the Deputy Leadership of the Labour Party in 1981 was heavily criticised by Labour's leader Michael Foot, who had long been associated with the Labour left and Tribune Group. Tribune Group member and future Labour leader Neil Kinnock led a number of Labour MPs to support John Silkin in the deputy leadership election and abstain in the run-off between Healey and Benn. This sowed the seeds for a split in the left between a "soft left" supportive of Foot's leadership and a dissenting "hard left" organised principally around Benn.

The Campaign Group would go on to back Eric Heffer and Michael Meacher in their unsuccessful bids for the leadership and deputy leadership in 1983. The Campaign Group subsequently organised itself around opposition to the direction the party took under the leadership of Kinnock and his successors. An advertisement in Tribune (24 April 1983) gave the membership of the Campaign Group as: Norman Atkinson, Tony Benn, Ron Brown, Dennis Canavan, Bob Cryer, Don Dixon, Martin Flannery, Stuart Holland, Les Huckfield, Bob Litherland, Joan Maynard, William McKelvey, Andy McMahon, Bob McTaggart, Michael Meacher, Bob Parry, Ray Powell, Reg Race, Allan Roberts, Ernie Roberts, Ernie Ross, Dennis Skinner, and John Tilley.

Neil Kinnock was hostile to the Campaign Group. He pursued a "carrot and stick" approach to undermining the Campaign Group by promoting MPs who were willing to leave the Campaign Group and renounce their previously held views and by isolating those who remained members.

"From the day Kinnock became leader he made it clear that membership of the left wing Campaign Group of Labour MPs would be a bar to promotion within the PLP. He also made it clear that public repudiation of the group would be amply and swiftly rewarded. Jeremy Corbyn, Labour MP for Islington North and for many years Campaign Group Secretary, remarked that the group was the biggest job creation scheme in the Palace of Westminster. Nearly every one of the twenty-odd ex-members of the Campaign Group sitting in the 1987–92 Parliament was appointed to the front bench shortly after leaving the group."

During the 1984–85 miners' strike, MPs from the Socialist Campaign Group took action to support the striking miners by visiting picket lines and raising money to be donated to the miners' relief centres. This put pressure on the Labour Party leadership to support the strike, something Neil Kinnock resisted until 10 months after the start of the strike. Members of the Socialist Campaign Group also led a "direct action protest" in the House of Commons by refusing to sit down in order to force a debate on the strike.

In 1989, the third Conservative Government of Margaret Thatcher announced plans to introduce a flat-tax to fund local Government. The planned tax became known as the poll tax and was thought by many to be intended to save the rich money and move the expenses onto the poor.