The Equality Trust was founded in 2009 by Bill Kerry, Richard Wilkinson and Kate Pickett.

The idea for the Trust was developed in 2007, after Richard and Kate secured a publishing deal for The Spirit Level: Why more equal societies almost always do better and Bill recognised the potential for a campaign based on their evidence. They established an Advisory Group to help them shape the organisation and worked with the Sheila McKechnie Foundation to develop their vision and strategy.

In 2008 the Trust was awarded two-year funding by the Joseph Rowntree Charitable Trust which enabled the founders to commission a new website from e-campaigning experts Advocacy Online and employ their first member of staff, Kathryn Busby, as Policy & Campaigns Manager.

Kathryn started work in February 2009 and The Equality Trust's launch coincided with publication of The Spirit Level on 5th March 2009.

In November 2009, a new short-term campaign called One Society was set up in association with The Equality Trust, to highlight the negative effects of income inequality, showcase research and policy solutions, and bring together people and organisations in support of a more equal society in the run up to the 2010 General Election.